A Complete Dr. Zeng Mystery Novel

Blackmail Clinic

By Walt Bruce

A Nazi "truth serum" proves a boomerang when Dr. Zeng Tse-Lin invades the precincts of treachery in a daring campaign to clean up a sinister nest of murder and espionage!

CHAPTER I
DEATH TO THE FEDS

THE night was ominously dark, with just enough fog in the air to veil the stars in shroud-like semi-concealment. All around the Bay Area, spectral fingers of white glow probed weirdly into low-hanging mists, moving and stabbing and shifting. These were the antiaircraft searchlights bearing mute witness to the alertness of a nation at war.

It was strange, Steve McCune thought, how San Francisco had changed. Once upon a time its brilliance and light could have been seen for miles, but now the city's glitter was dimmed down to a mere ghost-reflection. This waterfront street, for example, with its electroliers hooded and all neon signs doused by order of the Army Interceptor Command, was like a shadowy gullet waiting to swallow the unwary traveler.

McCune shivered a little and wished for the full power of his small coupé's headlamps instead of the undersized, fender-mounted parking lights which were all the law permitted you to use after nightfall in this neighborhood. He felt worn and weary as he drove slowly home from the shipyard where he was employed; weary, and vaguely uneasy.

IT was past midnight, and Steve McCune had good reason to feel tired. In recent months he had been on the swing shift, starting work at four in the afternoon and quitting at twelve. That usually made it around one in the morning before he got home to the old house where he lived with his family.

Sleep was difficult under such conditions. True, he had remodeled the attic into a makeshift bedroom for himself in order to get as far away as possible from daytime traffic noises. But even so, it was hard to obtain the proper amount of rest when everybody else was up and stirring around.

He yawned as he drove; shivered again, although the night was not cold. His sensation of uneasiness persisted, crawling through his marrow like a slithery premonition of impending disaster. His mouth twisted wryly as he thought about his job as foreman of the big shipyard's blueprint department.

It was a good job, an important job, the sort of work which made a man feel that he was valuably contributing to his country's war effort. For the yard was constructing a new and secret type of Q- boat for the Navy, breaking all records in the speedy fabricating of these hush-hush antisubmarine weapons. McCune had thoroughly enjoyed his part in the vast program until a certain thing had happened.

He swore silently, remembering the ugly circumstances that had enmeshed him. Then he glanced at his rearview mirror and went suddenly tense as he saw the hooded lights of a car behind him. There could be no doubt about it, now. He had suspected it for the past several blocks. He was being followed.

"They're after me!" he whispered.

HE INCREASED his coupé's speed, his palms sweaty on the steering wheel and tiny beads of cold perspiration forming on his forehead. Had the showdown come at last, he wondered? He set his lips grimly as the car jounced ahead over rough paving, and the worry that had been cutting deeper and deeper into his consciousness the last few days was a living, growing cancer gnawing its way into his brain.

He twisted to the right at the next intersection, then right, and left, and left again. He knew these waterfront streets. As a kid he had played through the district. Growing older, he had run errands and then driven trucks for the wholesale markets. He was as familiar with the alleys and byways as he was with his own home.

But turn as he might, the pursuing sedan matched every maneuver. It kept pace with him like a relentless burr. It did more than keep pace? it was gaining on him, coming closer, narrowing the distance with every revolution of its humming tires.

With a sort of dread hopelessness, Steve McCune realized the futility of any attempt to escape. For days he had tried to avoid this decision, but now it had caught up with him.

He was not armed and, in some respects, that fact was a relief. Had he been carrying a gun, he might have been tempted to use it. As it was, he slackened speed and resigned himself to the inevitable.

The trailing car drew abreast, angling McCune toward the curb. A white beam of light cut through the darkness to strike him directly in the face.

"Pull over and stop!" a grim voice called. "No tricks."

He obeyed, braking to a halt and cutting his ignition. The sedan was clamped down alongside, its front door was punched open and a big man in a topcoat swung to the street, a gun glinting in his clenched fist.

"Your name McCune?" he demanded.

"Yes," was the defense worker's answer.

"Steve McCune?"

"That's right."

"Get out," the big man said quietly.

McCune complied, instinctively raising his hands as he faced his captor.

Meanwhile the sedan's driver had slid from behind his wheel. Now he loped around to run quick, expert hands over McCune's pockets from behind.

"No gun," he announced, and stepped back a pace.

McCune tried to keep his voice steady.

"What is this?" he demanded.

"You're under arrest," the big man in the topcoat answered bleakly.

He extended his free hand, palm cupped so that the shape of a small gold shield could be made out.

"Department of Justice?the F.B.I.," the big man said, and there was no expression in his tone as he spoke.

McCune's shoulders twitched and his mouth felt dry, his throat tight. It had come! This thing he had been dreading had finally overtaken him. In a way, he was almost glad. At least it ended all the troubled uncertainty which had held him in its grasp.

He was seized with a sudden hysterical impulse to shout, to explain that he had been trying for days to make up his mind to go down to the Federal Building and make a clean breast of the whole rotten business. Which was true enough. He had wanted to confess to the authorities, but fear had restrained him.

Now he could talk. Now he could tell what he knew. He would be protected.

He opened his mouth to speak. The words were never uttered, though.

NOISELESSLY and without lights, a third automobile had drawn abreast of the spot, a black limousine which had coasted to a standstill with a dead motor. A blasting blurt of gunfire pulsed abruptly from this hearse-like vehicle, a yammering thunder of explosions, sharp and staccato as the crack of doom.

Steve McCune's movement was a reflex action. His knees went slack and he dropped to the pavement like a cut rope and rolled under the sheltering bulk of his own coupé. Bullets sang and whined and ricocheted around him, pinging off the sidewalk and the wall of a warehouse beyond. But for the moment, McCune was safe.

The Federal agents were not so lucky. In that first withering rain of slugs the big man in the topcoat had gone down, riddled through the chest.

His companion lurched under the impact of hot lead, but managed to stay on his feet and pull an automatic. He snapped six quick shots at his attackers. Then, like a jackhammer riveting steel, a submachine-gun opened up from the limousine. Steady tongues of flame stuttered out of its muzzle and the second F.B.I. operative doubled over as if he had been chopped in half. He fell sprawling, motionless.

And still the tommy-gun kept up its stammering clatter, pouring a hail of metal into the bodies of the fallen Feds. The two corpses danced a macabre rigadoon as the bullets smashed them.

Then, abruptly, silence settled as the weapon clicked empty. The limousine's motor roared alive and its gears clashed it into forward motion. Like a thunderbolt projectile it surged ahead and vanished around the next corner on tires that screeched soprano protest.

Steve McCune dragged himself from under his coupé and staggered upright. In the chaos of his mind there was no thought of his own troubles, now. He was too stunned, too dazed by the hideous scene he had just witnessed to think of himself. He bent over the two F.B.I. agents where they lay like dark, unmoving blotches in the gutter.

No use calling for medical aid, he realized. Both men were dead.

McCune stood by the riddled bodies, a great riptide of anger smashing through his heart and distorting his judgment. His first impulse was to leap into his coupé and pursue the murder limousine. But even as he whirled and raised one foot to the running board he realized the hopelessness of such pursuit. By now, that death car was long gone. It would be impossible even to guess which way it had headed after disappearing around the first turn.

A new thought blossomed suddenly in McCune's brain, one that made him almost ill. These men, these slain Federal operatives, had been sent to arrest him. Now they were dead? murdered! Maybe he would be accused of the double killing. Maybe a homicide charge would be added to the other thing he had been fearing.

Shakily he got into the coupé, started its motor. His hands trembled as he shifted gears, and his foot was jerky on the clutch pedal. It was torture to be caught between two fires, as he was. On one side loomed the law; on the other side were those enemies who were responsible for McCune's present predicament?enemies who would stop at nothing to gain their evil ends. They had proved that a moment ago with a death-dealing tommygun.

McCune was afraid. He admitted it to himself. Nor was he thinking only of his own safety. There was his mother to consider, and his brother Don, and the younger kids. He debated the wisdom of driving straight to the Federal Building right now and giving himself up, telling exactly what had happened, confessing everything he knew about the whole sordid affair.

Would the Government men believe him, though? Would they believe that he'd had nothing to do with the killing of the F.B.I. agents who had been assigned to take him in custody?

"No!" he whispered grimly. "I can't risk it!"

THAT was his terror talking, advising him to go home and think it over until morning. Then it would be time enough to surrender. For the present he needed freedom. Freedom to consider all the angles, maybe to warn his family and take them into his confidence, ask them what he ought to do.

That was it. He would go home to the safety of his attic bedroom, where he could think in the bright light of his reading lamp instead of in the depressing, malignant darkness of this dimmed-out waterfront street.

He swerved his coupé across Market, up the hill, and into his own garage. Below him the city fanned out, sinister in its silence. Matching that silence, McCune removed his shoes before he entered the house. He didn't want to awaken anyone now. In solid darkness he edged up the stairway, pausing when a tread creaked under his weight. Sometimes his mother woke up when he came in. Sometimes she would question him about the night's work.

He wanted no questions tonight. He wanted to see nobody. What he needed was to be alone, to ponder the problem confronting him.

He climbed the steep attic steps, fumbled his bedroom door open, stepped over the threshold, closed the door, and turned on the light. There was sanctuary here in these familiar surroundings. He stood still for an instant, breathing deeply of the peace and orderly cleanliness of the place.

So complete was his concentration that he did not hear the small shuffling sound behind him?the rustling noise of a rope being paid out. He did not see the hangman's noose at the end of the peculiarly knotted rope, nor did he guess that he was not alone in the room until the loop was dropped over his head and drawn tight about his gullet.

He tried to turn, then, but it was too late. His hands came up, clawing desperately at the hempen cord which was strangling out his life. His struggles were fruitless. A brutal knee was jammed into the small of his back. The noose cut into his windpipe.

Steve McCune went limp.

CHAPTER II
DR. ZENG TSE-LIN

CHINATOWN, that mysterious sector of San Francisco rumored to conceal a thousand secret passages and twice that many weird Oriental customs, was as dimmed-out as the rest of the city. The streets were almost entirely deserted at this late hour, and all shop-window lights had long since been turned off.

The Mandarin Emporium, one of the biggest establishments in the area, was no exception to the rule. Its windows, filled with Asiatic objects of art, were tightly shuttered. No trace of illumination could be discerned either downstairs or on the upper floors of the "House of a Thousand Beatitudes" which comprised the residence portion of the building.

But there were lights behind the shrouding curtains of heavy black silk which masked those upstairs windows. For this was the home of that mysterious Chinese physician known as Dr. Zeng Tse-Lin, a man whose vast wealth was exceeded only by his learning. Despite the lateness of the hour, Dr. Zeng was seated in a low teakwood chair, studying the brush marks of an ancient Chinese parchment manuscript.

Zeng was a tall man who looked even taller in his brocaded robe of Oriental silk and his black skullcap with its green button denoting a fifth examination scholar who possessed degrees from the finest Chinese universities. His ascetic face was hawk-like, and his dark eyes glowed weirdly with imponderable depths of knowledge.

Through his studies in American as well as Asiatic schools, he had attained mastery of every known science and art. There also were whispered rumors that he sometimes dealt in black magic as well as in medicine and surgery.

Such rumors were bound to surround a man as mystifying as Dr. Zeng Tse-Lin. It was only natural that his Chinatown friends and neighbors should wonder how anybody as young as Zeng could have acquired so many diplomas from so many colleges throughout the world. How could a man scarcely more than thirty be a master surgeon, an internationally famed scientist, an inventor whose patents had already brought him uncounted riches? Surely there must be magic in such a fellow!

In a sense, Zeng actually possessed a magic touch?but it was a magic gained through study of all branches of Oriental and Occidental lore, ancient and modern. That was the true secret of his multifold abilities, just as constant rigorous exercise was the secret of his splendid physical stamina, his superlative strength and his inexhaustible endurance. But of all the rumors which circulated concerning this amazing personage, there was one fact nobody had ever guessed?

Dr. Zeng Tse-Lin was actually a white American whose real name was Robert Charles Lang!

True, Zeng had been born in China. His parents, though, had been affluent American missionaries slain by hoodlum Jap soldiers in the sacking of Shanghai. Zeng himself had been in the United States at that time, completing his education. Upon hearing that Nip thugs had murdered his mother and father, he had vowed his life to vengeance against all wrong-doers, all killers, all criminals.

In consequence, he had made an exhaustive study of the science of detection and had devoted himself to a secret career of bringing lawbreakers to justice. Ostensibly he was a Chinese physician of splendid attainments, respected by all who came in contact with him. Outwardly he appeared to be a man who operated the Mandarin Emporium as a sort of hobby. But his medical practice and his Oriental art shop were merely shields to mask his real activities as one of the greatest criminologists the world had ever known.

HE GLANCED up from the faded parchment he had been reading, and smiled at a ponderous individual who lumbered toward him. This was a veritable giant of a man bearing a paper- fragile bowl of steaming, fragrant pearl tea. This towering, moonfaced giant was Dr. Zeng's trusted servitor and friend, a Mongol warrior named Lai Hu Chow.

There was affection and sincere regard in the look which Zeng bestowed upon the approaching Mongol. Chow was a hulking, happy, childlike fellow whose features bore the scars of many hatchet battles, and who walked with the rolling gait of a tipsy sailor.

His rakish stride was not the result of too much rice wine, however. He had lost a leg while fighting the Jap hordes who had murdered Zeng's parents, and now he wore an artificial limb which Dr. Zeng himself had constructed.

Just as this artificial leg was a part of Chow's life, so was Chow a part of Zeng Tse-Lin's existence. In peaceful pursuits or in war against crime, the two men were inseparable companions.

"You stay 'wake too late, you dlink tea to keep flom getting sleepy," the giant remarked, offering the steaming bowl. "Is better you go to bed, get some rest."

Zeng sipped the hot infusion.

"You may retire if you wish," he answered in high-caste Mandarin dialect. "As for me, I expect a visitor. A certain young man telephoned me earlier this evening, and he sounded troubled. I invited him to call."

"Somebody sick, got bellyache, maybe?"

"His illness seemed more of the spirit than the body. I can tell you more when I have talked to him. Hark! There is the door chime now!"

Chow grumbled something about foolish persons who chose one o'clock in the morning to pay social calls.

"I go open up," he said.

"No, wait a moment." Zeng closed the ancient parchment and arose from his teakwood chair. "It is written that the wise man looks first before unbarring his portal, lest a tiger enter in the guise of a friend."

As he spoke, the doctor with the hawk-like face lifted the ornately carved lid of a large ebony box on the table. Inside this box there was a ground glass screen which grew luminous at the touch of an electrical control. By a series of wires leading down to the front door, connected with special selenium scanning discs, and activated through the grids and plates of electronic tubes, the ground glass screen now reflected the features of the man on the outer steps?the visitor who had pressed the button of the doorbell.

This viewing apparatus was Zeng's personal adaptation of the television principle, whereby he could scrutinize all callers before admitting them. In Chow's secret estimation it was a device of Satan rather than science, and he didn't like any part of it. He didn't say anything, though. If such inventions suited Dr. Zeng, then Chow had no objections. He merely refused to look into the machine.

Zeng himself did not peer long at the glass. He saw the night-blurred reflection of a young, freckled, red-haired man whose jaw was rugged and whose eyes were forthright.

"It is truly the one named Don McCune," he murmured. "You may admit him, Chow."

"Don McCune?" asked Chow. "Works at gasoline service station on the corner down street?"

"The same. Make haste to admit him."

PRESENTLY Chow conducted the broad- shouldered visitor into Zeng's upstairs living room, poured another bowl of tea and bowed himself out. Immediately Dr. Zeng shook hands with himself in the accepted Chinese fashion as he smiled at his caller.

"Welcome to my inferior dwelling, young sir. Partake of my woefully bitter tea and tell me what troubles you."

Don McCune accepted the fragrant cup and tried to mask his worry behind a grin.

"It's good of you to let me come up, Dr. Zeng. I'm probably being a fool, but?"

"It is written that he who knows he is a fool has much wisdom. Speak what is in your heart."

"Well, it?it's my brother, Steve. He works at a shipyard across the bay. I?I don't exactly know how to put it in words, but?well, something's the matter with him. Something serious."

"Such as?"

There was a noticeable hesitation in Don McCune's answer.

"It started with the clinic," he said.

"What clinic?" asked Zeng curiously.

"The one in the old building opposite my gas station. A bunch of doctors and surgeons and dentists organized it two or three months ago as a sort of group insurance health service for folks employed in war industries. Naturally I heard a lot about it, because some of the people from there bought gas and oil from my station. So?well, I persuaded Steve to join it."

"There is nothing wrong in that, if you thought it was a good thing for him."

McCune nodded. "I did think so. Especially when I knew plenty of other shipyard workers had joined. Then, a few weeks ago, Steve had a heavy cold and went to the clinic for treatment."

"And?" Zeng's dark eyes glittered expectantly.

"I noticed a change in him almost right away. I don't mean in his health. He got over the cold soon enough. But he used to be a happy sort of guy? merry, carefree, always joking. Then suddenly he turned sullen?I guess morose is the word I want. Kept to himself. Seemed to be worried stiff. We all noticed it?Mom, and the kids, and . . . well, anyhow, I got to thinking maybe they had given him some medicine at the clinic that wasn't good for him. A bad prescription or something. He's been losing weight, and he don't sleep well, and he can't eat."

Zeng frowned thoughtfully. "Let me understand this. Are you asking me to pay your brother a professional call in my medical capacity? That would be contrary to ethics. One doctor is not supposed to examine another's patient unless the attending physician invites him in for a consultation."

"I know that," Don McCune answered, his eyes straightforward. "I thought you might make an exception in this case, though. Miss Ann Carter suggested it when I spoke to her at the mission school."

CHAPTER III
SPURIOUS SUICIDE

MENTION of Ann Carter's name turned Zeng's frown into a smile. Ann was the niece of Captain Brian Carter of the San Francisco Homicide Bureau, and Captain Carter was Zeng's closest intimate. They had worked together on many a puzzling crime, and Carter was the only person other than Lai Hu Chow who knew the true secret of Zeng's white parentage.

Moreover, Ann Carter meant a great deal to Dr. Zeng Tse-Lin. Possessed of an income sufficient unto her needs, she devoted her life to a mission school here in Chinatown for underprivileged Chinese children. Zeng admired her for this splendid work, and he admired her even more for her sweet nature, her piquant beauty, her competent self-assurance.

In fact, he never thought of Ann without experiencing a quick surging in his heart. Long ago he might have declared his love for her, except that one fact had always restrained him. His life was consecrated to a never-ending battle against crime, a battle which exposed him to constant peril. He could not bring himself to ask Ann to share that peril, to risk her own safety.

Therefore, he had never let her know how he felt toward her. Instead, he concealed his feelings behind a mask of Oriental reserve, allowing her to believe he was Chinese. This artificial racial barrier served to bar all thoughts of romance.

Just the same, Ann had only to express a wish and Zeng stood ready to obey. So it was now. He peered keenly at Don McCune.

"I am to understand that Miss Carter asked me to take a hand?"

"Yes, sir. You see, this isn't just an independent case. Hundreds of other war workers go to the clinic. If the treatment has the same effect on them that it's had on my brother Steve . . . well, the damage could be serious in lost man-hours and lowered efficiency."

The tall, sun-bronzed criminologist saw the truth of this, and he reached a swift decision.

"Very well. I shall be happy to talk to Steve. When would it be convenient?"

"Why, right now, I suppose." Don McCune's freckled face showed grateful relief. "He usually gets home from the swing shift around one in the morning. He ought to be there now. That's why I came here at this particular time. I was hoping you might go home with me, get it over with as soon as possible."

Dr. Zeng clapped his hands sharply, and Lai Hu Chow lumbered into the room.

"I eavesdrop at door," the giant said, and grinned engagingly. "You want limousine, eh? I go fetch, chop-chop."

And he went shuffling from the house, chuckling as if at some vast jest. The joke, of course, was his use of pidgin English when he could speak the American language as well as anybody. His master had painstakingly taught him. But he liked to tease Zeng by lapsing into garbled jargon.

"Just like Chinee laundryman when washee dirty shirtee," he said, laughing to himself as he went to get the car.

Fifteen minutes later, the limousine pulled up in front of the house which the McCune family had occupied for years. It was a three-story frame structure on one of the hills west of Van Ness, an old building that had survived the fire and was much the same now as it had been when first built in the early Eighties.

Leaving Chow at the wheel, munching a huge wad of chewing gum, Dr. Zeng followed Don McCune into the house.

"I hope we don't wake Mom," Don whispered. "She's worried enough as it is. Steve's room is in the attic and we'll go right up."

"Very good," Zeng answered. "Lead the way."

They gained the top of the steep attic staircase, and Don tapped lightly on a closed door. There was no response, and a bewildered expression crossed Don's freckled features in the glow from the dimly shaded hall light.

"Strange!" the younger man muttered. "Steve's always home by this time, and he's a light sleeper. Why doesn't he answer?"

"Try the knob," Zeng suggested.

DON obeyed, and the two men stepped over the threshold, only to freeze in sudden horror. Steve McCune was home, but he was not awake. He would never awaken again. His body dangled grotesquely from a hangman's noose about his neck, a rope which stretched upward to the rafters. . . .

The house was teeming with police within ten minutes. Downstairs, a grief-stricken family huddled numbly and tried to answer official questions as best they could. Up in the attic bedroom, Dr. Zeng conferred with his friend Captain Brian Carter, who had arrived posthaste.

Carter was a red-faced, chunky Irishman whose compact form was heavily muscular in its blue serge, and whose jaw jutted to bespeak the efficient courage which had brought him up through the ranks to become the head of the city's Homicide Squad.

"Of course, it was suicide, Zeng!" he growled. "Didn't Don just tell me how Steve had been moody and in ill health?"

"Quite so," argued Zeng. "And yet?"

"The thing's open and shut. Steve came home in a depressed mood. He decided to call it quits. He fastened a rope to the rafter, made a noose around his neck, stood on this chair, kicked the chair out from under him, and that was that."

Zeng Tse-Lin's ascetic countenance was impassive.

"Have you any familiarity with the work of a Belgian criminologist named Goddefoy?" he asked quietly. "It was he who first made a scientific study of rope fibers in cases of death by hanging. Assume that a killer wishes to make his victim appear to be a suicide. He loops a noose about the victim's throat, throws the rope over a beam and pulls his man upward, much the same as in the old Wild West necktie parties when a posse of lynchers would string up a cattle rustler."

"Well?"

Zeng shrugged. "In such an event, the rope's fibers will lay in the opposite direction to that of the pulling, due to friction with the beam or rafter. I have casually examined this rope by which Steve McCune's corpse was suspended. The fibers tell an interesting story. I think he was hanged by some other person."

"Poppycock!" Carter scoffed. Then he added apologetically: "Not that I doubt your beliefs, Zeng. You've been right too many times in the past for me to contradict you. All the same, how in thunder could I begin any investigation of a supposed homicide with no clues except the position of some rope fibers? The newspapers would laugh me out of office! And besides, I've already got enough grief on my hands."

"Ah. So?"

Carter made a bitter mouth. "Two F.B.I. agents were murdered by tommy-gun slugs less than an hour ago, down by the waterfront. My hands will be full of that investigation, working with the Federal Bureau. I can't afford to borrow more trouble by considering this Steve McCune case as anything but suicide. Not unless I get more concrete evidence than a length of rope with its fibers rubbed the wrong way."

"You would not object, though, if I were to make an independent survey of the McCune matter?"

"Not at all," Carter answered warmly. "You know I always welcome your help, old friend. Only this time you're off on a false scent, is all."

BOWING and shaking hands with himself, Dr. Zeng strode downstairs and out of the house. Before joining Chow in the limousine, however, the tall criminologist moved quietly to the rear of the McCune residence and entered its backyard lean-to garage. Here, using his pocket torch, he inspected the dead Steve McCune's little coupé.

The battered car's left rear fender seemed to interest him, particularly where it was marked by a sort of gash across its side. Zeng carefully examined this bright exposure of raw metal and knew that it must be of recent origin, for the salt sea air of San Francisco would have flecked it with rust discolorations within twenty-four hours. What, he wondered, had torn the fender so peculiarly?

In the midst of pondering the problem, he pivoted swiftly as he heard approaching footfalls. Then he saw young Don McCune coming toward the garage, drawn by the will-o'-the-wisp flicker of Zeng's flashlight.

"Oh, it's you," the younger man said wearily. "I came out to walk around and get my mind off? what happened to Steve. I saw your light, and?"

The Chinese doctor nodded. "I understand your sorrow, and it is distasteful for me to intrude upon it. Yet I am glad that you are here, for I wish to ask you a question."

"I'll answer if I can." Don's voice was apathetic.

"Then tell me Steve's usual course of travel from his work to his home. Would it perhaps be along the harbor district?"

"Why, yes. But I don't understand?"

"There are many things which defy explanation at the moment," Zeng said quietly. "Your brother's apparent suicide is one of them."

Don clenched his fists impotently. "I can't understand it, either. Steve was in a jam, I know, but he wasn't the kind of guy who would kill himself."

"Perhaps he didn't," the criminologist intoned.

"You mean?murder?" Horror was in young McCune's voice.

"It is possible."

Don stared. "Do you think those clinic doctors?"

"That remains to be seen," Zeng Tse-Lin answered. Turning then, he strode thoughtfully from the garage.

CHAPTER IV
THE FINGER POINTS

THERE were many secret avenues and devious channels through which Zeng obtained information when he so desired. Dawn was filtering across the eastern horizon before he returned to the House of a Thousand Beatitudes in Chinatown. During the intervening hours he had talked to many persons and visited more than one unpleasant place. Now, sending Chow to put the car away, he moved toward his front door with a brown paper parcel tucked under his arm.

"Zeng!" a feminine voice called to him from the recessed entrance of the shuttered Mandarin Emporium. And then Ann Carter darted into view. "I've been waiting for you!"

His heart leaped, as it always did when Ann was near. From her toeless pumps to her wavy auburn hair she was exquisitely dainty, and her slender curves were subtly emphasized by the tailored sharkskin ensemble she wore. One look at the pert insouciance of her face, the generous fullness of her lips and the steady depths of her fine eyes showed that here was a woman among women?a girl of character and breeding and intelligence, as well as youthful beauty.

With unaffected charm she offered Zeng her hand. He bowed over it.

"I am honored by your presence, which makes the dawn as bright as sunrise. But what brings you to me at such an early hour, Ann?"

"The McCune case," she answered, as he opened the door of his residence and courteously stood aside for her to enter. "Uncle Brian told me some of it, and then I called on the McCunes to see if I could help them in their trouble. Young Don said you'd interested yourself in his brother's so- called suicide, and I thought I'd come over to ask you if you've learned anything."

"I have learned many things," Zeng Tse-Lin said, as he conducted her up to his magnificently furnished living quarters. "And I think I have stumbled into a matter which has ugly ramifications. As yet, however, I cannot guess where the trail will lead."

Ann studied his ascetic countenance. "Would you care to tell me what you've found out thus far?"

"Gladly, if you agree not to repeat what I say. For the present I am reluctant to formulate a theory which would be concrete enough to offer to your uncle."

She smiled softly. "I'll keep mum, Zeng."

"Good." He began unwrapping his brown paper parcel. "To begin with, the unfortunate Steve McCune had charge of the blueprint department of his shipyard's swing shift."

"Yes, I know that."

"Secondly, this shipyard is constructing a new type Q-boat to combat Jap and Nazi submarines."

"I'd heard that, too," Ann said.

"Now we come to secret information. Recently, certain specifications and plans of those Q-boats have fallen into Axis hands. I shall not divulge the source of my information, but at least I can tell you that the F.B.I. has been investigating this leak."

Ann looked startled. "Do they suspect anyone in particular? I mean, somebody on the shipyard payroll? An employee?"

"They do," Zeng said slowly. "In fact, all members of the blueprint department have been under Federal surveillance for several days."

"Including Steve McCune?"

"More than that, Ann. It finally narrowed down until Steve was the only suspect."

HER eyes flashed indignantly.

"That's preposterous!" she declared. "Steve was a loyal American! His entire family is above reproach!"

"Nevertheless, the F.B.I. eventually reached the conclusion that Steve was the man who had been selling vital war information to the enemy. Tonight an order was issued for his arrest."

"Government agents were going to pick him up?"

"Yes, for questioning. But the two F.B.I. operatives assigned to the task were murdered on the waterfront. You understand, none of this will ever reach the newspapers. The Department of Justice does not believe in publicity when any of their agents are slain. Just the same, these two men were killed before they had a chance to arrest Steve McCune."

Ann's voice dropped to a whisper. "And then later, Steve was found hanging?as if he had committed suicide to atone for shooting the Federal men!"

"That would be the obvious theory," Zeng Tse- Lin said. "And I grant that it sounds plausible. So plausible, in fact, that this entire case might be closed and considered solved. Yet I cannot quite bring myself to believe it. There is something deeper here, something far more significant which I hope to uncover. And this shall be my first step."

He finished unwrapping the brown paper bundle and withdrew two objects of hardened wax. Ann Carter shuddered slightly when she realized that they were paraffin impressions of human hands.

"What on earth?"

"Among the places I have visited during the past few hours," Zeng told her calmly, "I included the municipal morgue, for an examination of Steve McCune's corpse. I made these paraffin casts of his hands. Come, Ann. Let us go to my laboratory."

She followed him to the next floor above, where three large rooms had been knocked into one. The walls gleamed with white tile, glass shelves, enameled workbenches and a bewildering array of scientific apparatus encompassing electronics, chemistry, photography, physics and lesser-known medical equipment.

Dr. Zeng immediately began a chemical experiment upon the two wax hand-casts. Presently he finished the job.

"No trace of nitrate stains," he remarked.

"Meaning what?" Ann asked him breathlessly.

"It proves that Steve McCune discharged no firearms recently. Therefore, he could not have operated the submachine-gun or any other weapon which killed the two F.B.I. men. And yet there were bullet scars on the fender of his coupé, indicating that he was on the scene when the murders took place."

"You think he witnessed the killings?"

"Yes. And perhaps that is why Steve himself was subsequently slain. From the condition of the rope which hanged him, I am convinced that he did not commit suicide."

Ann's eyes narrowed. "He was murdered so he couldn't testify against the ones who shot the G- men! Is that your theory?"

"Partially, yes," Zeng said. "There could have been a secondary motive. Let us assume that he had been working with Axis spies, selling them shipyard secrets. Let us also assume that these spies killed the Federal agents to keep Steve from being arrested."

"It's a horrid thought!" Ann shuddered. "I don't like it."

The criminologist with the hawk-like countenance smiled gravely.

"Neither do I," he admitted, "but it may be true. If so, the spies must have realized Steve's usefulness was at an end. The F.B.I. suspected him and tried to arrest him. In brief, Steve was now a marked man. For the safety of the spies, his death was necessary. Therefore, they murdered him and attempted to make it look like suicide."

"You make it sound reasonable," Ann admitted. "But now that Steve is dead, how can you hope to pick up the trail of the spies he was working for?"

Dr. Zeng turned from his laboratory bench.

"I have only one slender clue," he told her. "According to Don McCune's story, Steve's character changed after he had gone to a certain medical clinic for treatment. This clinic is operated exclusively for people employed in war industries. I think I shall investigate the clinic. . . ."

THE reception accorded Zeng Tse-Lin at the clinic a few hours later would have allayed almost anybody's suspicions. The chief surgeon, Dr. Ormand Tremayne, knew Zeng by medical reputation, and insisted upon taking him on a personally conducted tour of the premises.

Tremayne, a spare, lanky man who sported a bushy black beard and smelled pungently of medicines, seemed genuinely flattered by Zeng's visit.

"It's an honor to have a doctor of your standing show any interest in our work," he said respectfully. "My medical colleagues will be anxious to meet you."

"You seem to have a well-equipped building," the Oriental scientist answered, gazing at his surroundings.

Tremayne's bearded lips parted in a smile.

"We're rather proud of what we've accomplished in such a short time," he confessed. "You see, all of us would have gone into military service, except that each member of the staff is either too old, or suffering some physical disability which makes us unacceptable to the Armed Forces."

"And so you found another means to serve, eh?"

"Yes. Frankly, we were appalled at the conditions surrounding certain war-industry centers. True, there's a shortage of physicians all over the country, but in some localities where thousands of new workers have moved in for essential jobs, the lack of doctors was alarming."

"Therefore you established this clinic," Zeng said.

"Right. Any war worker, or any member of his or her family, can procure medical or surgical treatment as required, for a small monthly sum. I wish we had more with which to work. And I wish there were more doctors willing to follow our lead, opening up similar clinics in other war centers."

As he spoke, the bearded surgeon pressed a buzzer on his desk. A white-jacketed orderly entered the room.

"Yes, Dr. Tremayne?" he murmured, as he came to attention.

"Ah, Lester, will you please ask the staff members to step in here? Thank you."

The orderly made a half-gesture that might have been the beginning of a military salute?or perhaps another sort of salute consisting of an arm raised and outstretched, such as Nazis employ when shouting " Heil Hitler!" Whatever the man had intended to do, though, he arrested the motion before it was well started. But his stride was military as he left the office.

Presently Dr. Tremayne's two medical colleagues entered, clad in the white gowns which they had donned in preparation for the opening hour of the clinic, a few moments away. Tremayne introduced them. The short, tubby one was Dr. Max Ernst, a cherubic and amiably smiling man whose pate was as bald as a peeled Easter egg and whose voice was thickly guttural, heavily accented.

"I haf heard much apoudt you, Dr. Zeng," he declared. "Id iss a bleasure to make your aguaintance."

Zeng bowed politely in acknowledgment, then turned to the second man, Dr. Barton Barryman, a jockey-sized fellow of middle age whose graying hair and sunken eyes betrayed constant devotion to his profession. Barryman spoke tersely, in curt, crisp sentences.

"Honored to have you call, sir. Be glad to have you sit in when I start receiving patients. Welcome your diagnostic advice."

BEFORE Zeng Tse-Lin could either accept or decline this invitation, the bearded Tremayne dismissed his subordinates.

"I won't keep you chaps from your duties," he told them. "I just wanted you to meet Dr. Zeng, and to extend him every courtesy of the clinic."

After they had gone, he smiled at the man in the richly-brocaded Chinese robe.

"You see," he said apologetically, "we have so much to do, and we are so few. We're flooded every day with many more patients than we can handle."

"Then I mustn't interfere." Zeng arose. "Perhaps you'll allow me to return another time."

Tremayne chuckled. "Nothing interferes with our work, Doctor. We don't permit it. But if you'd care to inspect the clinic now, I'll have Hartman show you around. Hartman's our business manager. George Hartman. Wait here and I'll send him in. Meanwhile, if you will excuse me, I have my surgery to look after."

Then the bearded man went from the office, leaving Zeng alone in the room to think about the men he had just met. Could any one of them be linked with Axis espionage activities? Could any one of them be a triple murderer?

CHAPTER V
MYSTERY BOTTLE

EVEN as Dr. Zeng was considering these questions, the answer, unknown to him, was being enacted in a basement storage room beneath his feet. Down there in that cellar chamber, four men were gathering, four men robed from neck to toe in white surgical gowns, their faces completely concealed behind sterile gauze operating masks, their heads covered by white caps. Shapeless in these disguising costumes, the four were seemingly as alike as quadruplets except that some were tall, some short. Whether they were stout or thin it would be hard to guess.

One, apparently, was in command. He spoke tersely.

"Don't like the idea of this Zeng fellow coming here."

"Why not?" another asked. "He's just a Chinese doctor, isn't he?"

"Yes. But did you see this morning's paper? Tells how Steve McCune's body was found hanging. Steve's brother Don made the discovery."

"Well?"

"A Chinese medico named Zeng was with Don at the time," the leader snapped.

"Gott in Himmel!" came from behind the gauze mask of another member of the gathering. "Couldt it pe der same man?"

"Must be. No other Dr. Zeng in San Francisco. Mighty funny coincidence he'd come straight here?unless he suspects there's a connection between this clinic and Steve's death. Maybe he's a police stool. Who knows? Point is, I don't trust him. Want him watched every minute he's in the building. Want him tailed when he leaves. Understand?"

Three heads nodded in unison.

"Good," the leader snapped. "Now get to your places. It's one minute of eight."

His underlings faded from the underground chamber as silently as three white-clad ghosts. Not until the last one had departed did the leader make for the door. He glanced at the outer passage, made sure it was empty, then quickly removed his mask and hurried toward a staircase just as a clock somewhere in the upper reaches of the building struck eight deep-throated times, marking the opening of the clinic's day. . . .

George Hartman, the business manager of the enterprise who had been assigned by Dr. Tremayne as Dr. Zeng's escort, was an elderly and affable individual with a hint of brandy on his breath and a tiny network of veins showing beneath the skin of his somewhat bulbous nose. His clothing, while of obviously excellent quality, looked as if it had been slept in.

His eyes held a gratified twinkle as he introduced himself to Zeng Tse-Lin. In a way, he reminded Zeng of the sort of person pictured when the words "old-time newspaperman" are heard.

Hartman was not a former journalist, though. He was a promoter, a business go-getter, an expert organizer?exactly the type of man needed to direct the manifold activities of an organization such as this clinic. And if he performed his duties efficiently, what did it matter if he liked his breakfast coffee laced with a pony of brandy?

Garrulous, almost naively gabby, he kept up a running fire of chatter as he conducted Zeng through the clinic.

"Great thing, a place of this kind. It brings medicine and surgery down to the low-pay level that workingmen can afford. Health, sir?that's got to be America's watchword today. Keep the workers healthy, I say, and you keep them efficient and productive. Here's our X-ray room. We're mighty proud of it. Everything modern. Just look at this equipment, sir!"

Dr. Zeng smiled politely. "Excellent." But his eyes did not smile. They were busy scanning the Roentgen-ray room for possible clues.

Hartman beamed at his noted visitor's words of approval.

"Glad you like it, sir. Now come this way." He seemed as vain as a circus owner exhibiting a new gorilla. "This is the main operating room. Major surgery. And over here is another, for minor jobs of meat-carving . . . oops, excuse me. For a minute I forgot you were a doctor yourself. Maybe you don't like your profession to be kidded."

"I don't mind." Zeng smiled again.

"Gosh, thanks. I wouldn't want to hurt your feelings. Now see those three doors over there? That's the doctors' consulting offices where they receive their patients. We won't go in if it's all the same to you. They're all pretty busy this morning. Lots of colds and flu floating around these days."

Zeng Tse-Lin nodded. "Quite all right. By the way, what are these three alternate doors between the three medical offices?"

"Dispensaries," Hartman said pridefully. "My own idea. Each doctor has one. When we first started, we wasted a lot of time sending what medicines they needed from the main stockroom. Now, for most drugs, each doc can get what he wants from his own dispensary. Here, I'll show you one. Belongs to Dr. Ernst."

"He's the little fellow, bald, speaks with a thick accent?" Zeng asked.

"Yep. Great guy, too. Used to be in some hospital in South America for a big oil company. Came to San Francisco as soon as the war started, ready to do what he could to help."

The Oriental criminologist was listening with only half his attention. His piercing black eyes were busily surveying the little dispensary room with its tiers of shelves containing bottled medicines and drugs.

Zeng possessed the uncanny faculty of being able to photograph a scene with his vision, indelibly engraving it upon the sensitized plates of his memory. One sharp glance was sufficient for his purpose. Years later, he could have accurately named every label on every bottle of the hundreds on these shelves, even specifying their positions.

Now, unknown to Hartman, he performed this amazing visual trick. Then he turned courteously to the clinic's gabby business manager and seemed to devote his entire concentration upon what the man was saying. But in actuality, Zeng was studying his mental photograph of the room, sorting and classifying all the drugs he had briefly seen.

Presently, under the microscopic scrutiny of his superlative memory, he came to one bottle which arrested his thoughts in midstream. It was a glass container labeled "Fluid Extract of Ergot," under which designation appeared a chemical formula.

That was a queer thing, he decided. Of what earthly use could ergot be in a clinic of this sort? True, the stuff had recently been used experimentally in the treatment of idiopathic migraine?that is, headaches without apparent causation?but with inconclusive results. The principal use of ergot in medicine was such that it would scarcely be expected to be in use in the treatment of colds and like ailments of war industry workers!

There were two other glaring errors about that bottle. Ergot was a derivative of rye fungus and, therefore, had no chemical formula. Yet this label boasted such a formula, which was absurd under the circumstances. And finally, the substance in the bottle was white, crystalline?not at all what ergot looked like. Therefore the bottle contained something else. Either the label had accidentally been pasted on the wrong bottle, or it was a blind to conceal the nature of the real contents.

WITH a lightning movement, swifter than the cleverest feat of a vaudeville magician, Zeng reached out of the shelf where the bottle stood. He palmed the container, thrusting it up into a capacious sleeve of his brocaded robe?and at that precise instant, two doors opened into the dispensary.

One was the portal of Dr. Max Ernst's adjoining office, and Dr. Ernst himself appeared at the threshold?seeking a bottle of vitamin tonic, he explained. Simultaneously the corridor door opened and the white-jacketed orderly, the man named Lester who had seemed on the verge of giving a Nazi salute a while before, stepped into the room with a message for Hartman.

Zeng repressed a frown; kept his features expressionless. Had either of those two men witnessed his purloining of the fake ergot vial? For that matter, had Hartman himself seen the movement? He couldn't tell. At least, none of the three men gave any indication of knowing what had happened.

A few minutes later, having completed his tour of the clinic, Zeng Tse-Lin followed Hartman into the business manager's own private office. The garrulous Hartman smiled happily.

"Quite a layout, eh, Dr. Zeng?"

"Admirable. But I am curious to know how you handle so many patients and keep their records straight. You must have a marvelous filing system."

Hartman beamed. "We have, sir. I installed it myself. Let me show you."

He conducted his visitor into a connecting room lined with steel filing cabinets crammed with the card-index dossiers of every person the institution had treated. They were arranged alphabetically by names, then cross-indexed according to which attending doctor had given the treatment.

Ostensibly at random, Zeng opened one drawer and casually inspected the file cards. But it was no accident that caused him to select this particular drawer, nor was it coincidence when his long, spatulate fingers sorted out the card belonging to Steve McCune.

He seemed to glance at it for only an instant. But again his photographic memory made a snapshot of the entire record. With rising interest he observed that Steve McCune had been one of Dr. Max Ernst's patients.

Ernst, the physician in whose dispensary Zeng had just found the fake ergot bottle! Ernst, who talked with a German accent!

CHAPTER VI
KIDNAP BREAK

WHEN Lai Hu Chow drove his tall, hawk- countenanced employer back to the House of a Thousand Beatitudes a little later, it was at the top speed permitted by law. Dr. Zeng was in a hurry to get to his laboratory and test the white crystals in the ergot vial, for a fantastic theory was forming in his mind.

But he was prevented from immediately entering his dwelling, because just as Chow parked before the Mandarin Emporium, a loitering figure emerged from the doorway. He was an anxious- looking young man with red hair and an expression of tension on his freckled face?Don McCune. He moved quickly toward Zeng.

"Did you find anything at the clinic?" he asked earnestly. "Have you been there, sir? Have you any news for me about what was wrong with Steve?"

The tall, robe-clad criminologist made a silencing gesture.

"You must be patient," he advised gently. "It is written that the hare's speed sometimes carries him into the snare of his enemies, but a tortoise moves with the slowness of safety."

"Meaning you've nothing to tell me?"

"Very little." Zeng's sonorous voice was compassionate. "I have been to the clinic, yes. I have met the doctors there. More than that I am not yet prepared to say."

The younger man's lips drew into a bitter line. From the depths of his overwrought condition he spoke hotly in growing anger.

"You wouldn't be shielding these doctors, would you?"

"Shield them? Why should I?"

"You know why! You're a physician yourself. Medical men always stick together. I've heard that, more than once. It's the ethics of the profession? one doctor refusing to get another one into trouble!"

The criminologist smiled bleakly. "You misjudge me, Don. You speak without thinking."

"That's where you're wrong. Why shouldn't I be sore at all this delay, with the whole world believing Steve killed himself? I know he was murdered! So do you! I know the clinic was behind his troubles. The police think that's silly, but at least I figured I could count on you for help. Now it looks as if I'd made a mistake. I'm sorry I ever bothered you, Dr. Zeng. Sorry I came to you with my problems. Just forget the whole thing. I'll take care of it myself, in my own way."

With this final. outburst, young McCune pivoted and stalked off down the street, oblivious to Zeng's efforts to stay him. Zeng stared after him for a brief moment, then turned to Lai Hu Chow.

"Follow that youth, O Large One," he said in Chow's own native dialect. "Do not interfere with him, but report to me what he does and where he goes."

The giant Mongol nodded and sent the limousine sliding forward. Frowning, Dr. Zeng went into the House of a Thousand Beatitudes and ascended to his third floor laboratory, so preoccupied that for once in his life he forgot to make sure he had latched the front door at street level.

The moment he gained his scientific workshop he produced the bottle with the ergot label. Spilling some of the white crystals into a Pyrex beaker, he began adding chemicals, sharply watching the reaction.

The experiment engrossed him, required his undivided concentration. So he was not aware that an intruder had stolen into the laboratory and was skulking up behind him. Only when the muzzle of an automatic bored into Zeng's spine did he realize his jeopardy?and then it was too late.

"Easy, Doc," a voice rasped. "Unless you want me to let you have the big pill right now."

ZENG did not move. For years he had trained his muscles to perfect coordination, and he had long since ceased to permit himself the privilege of showing surprise.

"What is it you seek?" he said, his voice expressionless.

"You, mainly. And the bottle you stole from the dispensary. Turn around. Slow. And don't give me any lies. Why did you take that bottle? I know you got it. We were watching you."

"Why should I lie? The bottle is in plain view before you, on this bench. I took it because it aroused my curiosity and I wished to identify its contents?just as I can now identify you by your voice, before I have fully faced you. You are the clinic orderly named Lester."

As he said this, Dr. Zeng Tse-Lin turned cautiously and stared into the features of the man who had almost given a Nazi salute in the office of the bearded chief surgeon, Tremayne. No longer clad in a white hospital jacket, Lester looked chunky and solid in his street attire, menacingly muscular, to match the steely blue of his automatic and the gun-metal glitter of his unwinking eyes.

"So you were curious." His lips twisted sardonically. "That's why you stole the bottle."

Dr. Zeng nodded impassively. "And I am still intrigued, now that I have analyzed its crystal contents."

"Ah. Then you know what the stuff really is."

"Yes. Scopolamine?the so-called truth serum. A hypnotic drug used in cases of mania, delirium and insomnia, but in its hydrobromide form a crystalline sedative. Law enforcement agencies have used it experimentally to extract the truth from suspected liars, for under its influence a man's volition is temporarily suspended so that he cannot tell a falsehood."

Lester grinned unpleasantly. "Boy, are you smart!"

"I am not certain that I agree with you. I am still puzzled by the presence of such a little-used alkaloid in a clinic for war-industry workers. Of course, in view of recent events, perhaps I might hazard a guess. But my theory would be so completely farfetched and outrageous that I would doubt my own conclusions. For your sake, let us hope that I am wrong."

"It won't matter much whether you're wrong or right, Doc," Lester said significantly. "I think you've stepped in over your depth. In fact, something tells me you won't do anymore prying into other people's affairs for a long time to come. Maybe never. That depends on what the head man decides to do about you."

"Head man?" Zeng raised an eyebrow.

"Don't try to pump me. You'll find out soon enough what you're up against. I've got orders to bring you to the boss. Do you come without making trouble, or do I use my own judgment and blow you down right here and now?"

The criminologist's countenance betrayed neither fear nor alarm. He seemed completely without emotion as he answered:

"I seem to be in your hands, my friend. Your gun gives you the privilege of command. Unarmed, I can only obey your orders."

Lester stepped close, explored Dr. Zeng's brocaded robe for possible concealed weapons. Finding none, he backed off and thrust his own automatic into his pocket. But he kept his fist clenched on it so that it made a menacing bulge through the cloth.

"Okay," he grunted. "Let's take a ride."

"As you wish."

Zeng bowed slightly. And he strode toward the staircase with his captor at his heels, watching every move. Down on the second floor, in the living quarters, Zeng cast a veiled glance at a Ming dynasty water clock and was startled by the passage of time. More than an hour had fled since he had dispatched Lai Hu Chow to shadow young Don McCune, an hour that had been spent in chemically analyzing the scopolamine truth-serum crystals.

HOW long Lester, the clinic orderly, had been in the House of a Thousand Beatitudes, silently watching that chemical analysis, the criminologist could not guess. Of only one thing could he be certain?he had left his front door unlatched, and because of this oversight he had fallen into the hands of the enemy.

With the gunman at his side, he strode from the house and perceived a dark limousine parked at the curb, with a pock-faced man seated at its wheel. Pock-Face shot a quick look at Lester.

"Got him, eh? Any trouble?"

"Like taking candy from a kid . . . get in, Doc."

Zeng started to obey, but at that instant he noticed another limousine roaring in his direction. It was his own car, driven by the giant Chow.

Instinctively Chow seemed to realize that something was wrong. He knew it by Dr. Zeng's attitude, and by the menacing pose of the man named Lester, whose hand was in his pocket clenching a gun. With Chow, such a tableau called for direct action.

With a wild war-cry, the huge Asiatic mashed his throttle wide-open and sent his heavy machine yammering toward the kidnap car. Pock-Face, at the wheel of the parked automobile, saw destruction hurtling toward him with the weight of a juggernaut and the speed of a projectile.

It was more than human nerves could take. The driver of the snatch car shouted a hoarse oath of dismay, meshed his gears, and gunned his motor in a frantic effort to avoid the impending smash. He forgot all about Lester standing on the sidewalk with Zeng as a captive. He forgot everything except his own safety, and he sent his limousine screeching away from the curb.

This sudden desertion caused Lester a brief moment of panic?and that was sufficient for Dr. Zeng's needs. The criminologist whirled, brought a lashing uppercut full to the orderly's jaw. The jarring impact felled Lester like a pole-axed steer. He dropped in his tracks, unconscious.

Meanwhile, Lai Hu Chow swerved his oncoming vehicle at the last split instant, so that it barely grazed the kidnap limousine. The shriek of locked tires and squealing brakes made a knifelike din in the morning, and Chow's car swung around in a half-circle as he wrestled it under control. This gave the other machine a narrow margin of seconds, and Pock-Face took full advantage of it. He walloped his limousine around the nearby intersection at careening speed; vanished.

Chow should have followed, of course, but he was interested only in the safety of the man he served. Clambering to the street, he lumbered at an ungainly pace to where Zeng stood.

"How'm I doing? I bust up shenanigans quick, huh?"

"You did indeed." Zeng Tse-Lin smiled affectionately.

The big man stared at him. "You okay? Not hurt? You maybe want me to stomp this son of a camel until his face is strawberry pleserves?" He indicated the unconscious Lester.

"No. Merely lift him and carry him into the house before our neighbors are drawn by curiosity. I wish to question him without interference? perhaps by the use of that very truth-drug employed by his unknown chief."

Chow hefted the senseless orderly.

"Truth-drug?" he exclaimed when he had carried his burden indoors.

"Quite so. I shall not try to explain it to you now, O Large One. Soon you will see for yourself how it functions. When our prisoner regains consciousness I shall inject some of it into his arm, hypodermically. Then I think we shall learn many interesting things. For the present, take him down to our cellar and tie him securely."

THE giant complied, returning to Zeng and grinning as he reported the prisoner all safely fettered.

"What you want me to do now?" he added.

"You may tell me how it happened that you returned in the nick of time to save me from abduction," the Chinese doctor said. "I thought I ordered you to follow Don McCune."

"Sure. I followed him. That boy is plain fool. He went straight to clinic, started big fight with head surgeon."

Zeng's eyes sharpened. "Tremayne? The bearded one?"

"Aie. McCune collared him in doorway, called him names, said he was the one who had killed his brother, Steve. Bimeby Tremayne get plenty mad, you betcha. He grab McCune, give'm bummee rushee. McCune bounce on sidewalk like golf ball. Oh, boy!"

"Threw the lad out, eh? What did McCune do then?"

"Go for walkee along dockside. I followed him maybe-so for an hour. Nothing happen, so I come home."

"Fortunately for me." Zeng's ascetic lips parted in a faint smile. Then he grew grave. "I think it is time for us to experiment on the man we have captured. Perhaps under the influence of scopolamine he will tell me enough to clear up the riddle."

It took but a moment for the criminologist to go up to his laboratory, prepare a hypodermic and fill it with distilled water in which some crystals had been dissolved. And then, as he turned to descend the staircase, a muffled sound reached him?a sharp, distant report.

It could have been an automobile's motor backfiring, or it could have been a gunshot somewhere in the immediate vicinity. A sudden premonition inched through Zeng Tse-Lin's veins as he raced down to his living quarters.

"Chow! Did you hear that report?"

The giant nodded. "From cellar, seemed like."

In a burst of speed, Zeng descended to the ground floor and then hurtled down the steep steps to the cellar under the House of a Thousand Beatitudes. Dim light filtered from a high, barred window set into the basement wall at street level. This window?a narrow ventilator would be a better term for it?faced the alley at the rear of the building, so that anyone crouching in that alley could peer downward into the cellar.

That was exactly what had happened. Someone had peered down?someone with a gun. Someone had seen the unconscious Lester tied helplessly there, and had realized it would be impossible to rescue the prisoner. Therefore, to keep the man from answering any of Zeng's questions, a single bullet had been fired.

The bullet had penetrated Lester's brain, bringing him instant death.

CHAPTER VII
DEATH FOR A DOCTOR

IT WAS well past noon when Don McCune finally tired of his aimless strolling along the Embarcadero and decided to return to his home. In the interim, he'd had time to

regret many of his hasty words and actions.

He should not have spoken so harshly to Zeng Tse-Lin, he realized now. And he certainly should not have gone to the clinic and picked a quarrel with Dr. Ormand Tremayne. After the things Don had said to Tremayne, and the threats he had uttered, he scarcely blamed the bearded surgeon for throwing him bodily out of the building.

Maybe it would be a good idea, he concluded, to go back and apologize to Tremayne. And to Dr. Zeng as well. Certainly he had done himself no good by antagonizing them. You caught more flies with honey than with vinegar.

He turned, started walking back in the direction of the clinic. Before he had gone two blocks, though, a police radio patrol car drew up abreast of him.

"Just a minute, chum," a uniformed officer said.

"You mean me?"

"I think I do. Is your name Don McCune?"

"Yes. Why? What's wrong?"

The policeman sprang from the car. Something glittered in his fist. The glittering object was a pair of handcuffs. They clicked around Don's wrists.

"You're under arrest for murder."

"Murder?" The red-haired young man stared. "You must be crazy! I haven't killed anybody!"

"Save it. You admit you had a brawl with Dr. Tremayne a few hours ago, don't you?"

Don felt a sinking sensation in his heart.

"Yes, I?I had words with him. But?"

"So later you went back and caught him in his private office. You shoved a knife in him."

"That's not true!" Don shouted. "I never went anywhere near the clinic after Tremayne threw me out. It's true I threatened him. I suppose there were plenty of witnesses to that. But?"

The cop looked grim. "Maybe you've got an alibi. Can you account for your actions since you left the clinic?"

"N-no. That is, I've been walking along the docks, but I didn't see anyone I knew."

"Then let's go to Headquarters," the officer said. . . .

It was the hour of midday rice, but Dr. Zeng Tse-Lin was too busy to think about lunch. He was compounding some chemicals in his laboratory when he was interrupted by the tinkling of the telephone. He answered, and a warm glow stole through him when he heard Ann Carter's dulcet voice. There was tension in her tone, though.

"Zeng," she asked, "may I come to see you right away?"

His answer was unusually sharp, incisive.

"No! There is danger. I have enemies who might attempt to strike at me through you. You must not come here."

"Enemies?" Ann sounded puzzled. "What do you mean?"

HE DECIDED to tell her enough of the story to convince her she must stay away. "I am engaged in a certain investigation.

Because of an important discovery I made, there was an attempt to kidnap me. With Chow's help, I eluded the trap and captured one of these would-be abductors."

"Zeng! No!"

"It is true. A little while later, my captive was murdered by a shot through a cellar window?a most effective means of preventing his answering any questions I might ask."

"That's terrible!" Ann quavered. "Of course, you've notified the police?"

"Not yet. With all due respects to your uncle, he is an officer who believes in direct action. He might make moves at variance to my own plans. Therefore, I have told him nothing."

"But, Zeng?"

"There were two kidnappers," he continued quickly. "One escaped. Undoubtedly he has reported to his superiors in the organization which I am trying to uncover. The murder of my prisoner proves it. Consequently, these enemies realize that I am still at liberty and am seeking evidence of their identities, their guilt."

"You think they'll make another attempt on your life?"

"Very likely. It is a sort of duel. I am both the hunter and the hunted. So you must not come to my house. I cannot expose you to peril."

She sighed audibly over the phone. "I see. But I'm worried, Zeng?for your sake. I'd hoped to ask your help in another matter, but that's not important now. Nothing's important except for you to be careful. Promise?"

His heart leaped at this expression of her concern for his personal safety.

"I shall take no needless risks," he assured her. "But tell me why you wanted my help."

"It's nothing you can do anything about, now. Don McCune was arrested a while ago for murder.

Dr. Tremayne, the head of that war workers' clinic was found stabbed to death in his office, after Don had quarreled with him. But Don's innocent. I'm sure he wouldn't k-kill anybody!"

The Oriental criminologist scowled. So the bearded Tremayne had been slain after Don McCune had charged him with responsibility for Steve McCune's death! The news meshed into a pattern already forming in Zeng's mind.

Perhaps Don's angry words had aroused Tremayne's suspicions regarding certain aspects of the clinic. Maybe Tremayne had realized he was associated with a murder gang, and had undertaken an independent investigation within the medical group, without asking the aid of other doctors he was certain he could trust. There must be quite a number of such medical men associated with the clinic, in addition to those who had aroused Dr. Zeng's own suspicions.

Possibly Tremayne had stumbled upon some knowledge which made him dangerous to the real culprits. Therefore, they had knifed him to shut him up. And now Don McCune had been arrested for the crime!

"I am sorry to hear of this, Ann," Zeng said evenly. "If I can help Don, I shall. You may hear from me later."

And he rang off and returned to his laboratory work. . . .

IN a building not far away from the Mandarin Emporium, a man with a pock-scarred face sat on a camp stool with earphones clamped to his ugly head. He was that same Pock-Face who had driven the kidnap limousine a few hours before, the man who had deserted the orderly, Lester, after the failure of their scheme to abduct Zeng Tse-Lin.

He reached for a portable lineman's telephone, dialed it. Presently a voice answered him.

"Chief?" he said in a guarded whisper. "This is B-Two reporting. Good thing we tapped that Chinee doctor's line. I just heard him talking to some jane named Ann. She seems to have an uncle on the cops."

"What was the conversation?"

"He told her a little of what's happened, but covered up the details. He also said he hadn't told the police anything yet. I think he's wise to us, though. He savvies the score, even though he don't know who you really are."

"Hm-m-m. Got to stop that Zeng guy. He's dangerous. Slippery, too. But I think I know how to fix him. You say the wren's name was Ann and she's got an uncle on the cops? That means she must be the niece of Captain Brian Carter of the Homicide Squad. Yes?Ann Carter. Okay. Here are your instructions. . . ."

In his laboratory, Zeng was just stoppering several fragile glass vials filled with liquids. He summoned Lai Hu Chow and handed the vials to the giant Mongol.

"The leg of chemicals," he said enigmatically.

The words were no puzzle to Chow, however. He possessed an assortment of artificial legs, designed and constructed by Zeng Tse-Lin in bewildering variety, each created for a special purpose. All were hollow, cunningly contrived to contain various types of equipment. Some held guns, ropes, weapons. Others were the hiding places of bombs, gas throwers, shortwave radio transmitters.

The "leg of chemicals" merely meant a limb fitted with interior niches, lined with plush, in which fragile glass containers could be carried without breakage. Nodding, Chow took the vials and carefully departed with them, to return presently wearing a false leg laden with the thin glass tubes.

"We go smoke somebody out?" he inquired.

His employer smiled. "You speak more truly than you think, O Large One. I wish to inspect the case records of the clinic, and smoke will shield me. Come."

A secret subterranean passage led from Zeng's cellar under a row of store buildings to an exit in a blind byway a block away. The criminologist and his giant Mongol servitor used this underground passage now, for there was a possibility that the main door of the House of a Thousand Beatitudes might be watched by enemies. And Zeng wanted nobody to witness his present actions.

Clouds had gathered, masking the mid- afternoon sunshine and bearing a threat of storm, when he and Chow slipped into an alley behind the clinic building. There were several rear windows in the medical structure, two of them open. Making sure he was not observed, Zeng removed the glass vials from an aperture in Lai Hu Chow's false limb. Deliberately, one by one, he hurled seven fragile containers into the clinic.

The results were startling. Leaping flashes of red and yellow flame seemed to flicker within the building, as if a sudden holocaust had burst into blaze. Actually it was false fire, a chemical trick resembling flames but in reality harmless. Simultaneously, great billows of smoke spread through the clinic and poured from the windows.

ZENG TSE-LIN'S smoke bombs brought panic to the occupants of the building. Patients began streaming out through the big front door, followed by nurses and orderlies and the white-clad doctors themselves?the bald, pudgy Dr. Max Ernst and the jockey-sized Dr. Barton Barryman.

"Der whole blace iss going up!" Ernst shouted wildly, in his thickly guttural accents. "Everding iss lost!"

Barryman's terse, clipped speech cut across the pudgy physician's clamor.

"Sound alarm! Get fire engines. Where's George Hartman?"

"Right here!" The clinic's business manager divorced himself from the crowd of milling patients on the sidewalk. His face was flushed, and the veins on his bulbous nose looked more prominent than usual. "You didn't think I was staying behind to get cooked, did you?"

Barryman bristled like a truculent little bantam rooster.

"I want none of your misplaced humor, Hartman. Don't talk. Act! Get the Fire Department. Don't you realize we stand to lose every dollar of our equipment?"

Reddening, the business manager turned and scuttled toward a fire-alarm box on the diagonally opposite corner. Meanwhile Dr. Zeng, who had been watching this colloquy from the mouth of the alley, whirled and returned to the waiting Chow.

"The time has come for action," he said. "In with you through this rear window. I shall follow."

The giant blinked. "Okay. Me betcha we look like smoked sausage in two minutes bimebye, though!"

"Not at all. Those chemical fumes are bland, harmless. I prepared them so that they would appear thick, but in actuality we can breathe without difficulty."

As he spoke, Zeng leaped to the window, grasped its sill and chinned himself upward by main strength. His movements were so fluently graceful that they made the work of his superb muscles seem like child's play.

Chow followed, more clumsily. Then they were inside the smoke-filled clinic. By unerring instinct, Zeng led the way to the file room which Hartman had shown him earlier that day.

He knew exactly what he hoped to find. The index card on each clinic patient was a record of name, address, medical treatments received, and the doctor who had administered that treatment. Moreover, each patient's war-industry connection was indicated?the plant at which he worked, and the position he held.

Zeng knew these things because he had already superficially examined one drawer of the files this morning, under George Hartman's guidance. Now he wanted to inspect all the drawers, look at every card in the file.

His purpose was to select the names of all patients occupying key positions in war industries?men in charge of blueprints, for instance, or foremen of shops working on secret weapons and armaments. Having abstracted such a list of key men, he then proposed to visit them one by one, interview them and attempt to gain information which might substantiate his theories.

CHAPTER VIII
INJECTION OF TRUTH

UNTROUBLED by the chemical smoke which billowed around him, Dr. Zeng began his swift scrutiny of the index records. His amazing memory made it unnecessary for him to use pencil and paper when he wished to make a note of any certain name or address. Gradually he acquired a satisfactory list.

Then, presently, he came to the drawer which Hartman had shown him on his first visit here?the file records of all patients who had been treated by the bald, tubby Dr. Max Ernst. The criminologist's expert fingers riffled these cards, his keen vision taking a mental snapshot of each one. Then, abruptly, he frowned.

"There is something wrong here, Chow!" he said shortly.

"Is so? How?"

"This morning, when I looked at these particular cards while hunting Steve McCune's record, there were two more in the file by actual count than there are now. In other words, two cards have been removed since that time. Very clever. Very clever, indeed! It would have aroused suspicion if the entire file had been destroyed, but by removing

only two individual forms, our master criminal thought he was covering his tracks."

The huge Mongol shook his head.

"Chow dumbee like fun. No savvy."

"It's quite simple," Zeng answered grimly. "The two patients whose cards are missing must obviously be important to the mystery. Perhaps they were enmeshed and victimized in the same way Steve McCune was involved. By removing the index records of these two patients, someone hoped that the men would not be drawn into the investigation."

"Well?"

"The master criminal has made a mistake," Zeng Tse-Lin intoned. "He reckoned without my memorizing ability. In my mind, I will now run through the file as I recall it in its original state. I will 're-see' the two missing cards, read them, and have the information I need!"

As he spoke, he closed his hawk-keen eyes and went into an almost trance-like state of pure concentration which ended only after his superhuman memory had given him the results he demanded. Then he smiled without mirth.

"The end of the trail is in view," he told his giant servitor. "Let us go hastily."

Their departure from the clinic was none too soon, for fire engines were clanging in the outer street and heavy footfalls clumped into the building from the front. That would be the firemen seeking a nonexistent blaze, and a voice seemed to be leading them. It was a curt voice, sharp and terse?the voice of the undersized doctor, Barton Barryman.

"Bad enough our chief surgeon was murdered today. Now this fire?"

Zeng waited to hear no more. He nudged Chow to a rear window, watched the Mongol drop to the alley, then followed and landed as lightly as a cat. Together they sped around a corner and scuttled into an open passageway where stairs led downward to an underground maze?a labyrinth of twisting, turning tunnels which the criminologist knew by heart.

When they emerged above ground a few moments later they were directly beside the garage where Dr. Zeng's limousine was stored. He jumped into the car, gesturing Chow under the steering wheel and gave an address. Chow kicked the starter.

It was but a ten-minute run to the apartment house represented by that street number which Zeng's amazing memory had recalled.

"Stay here, O Large One," the robe-clad criminologist commanded. "I go to interview a man named Dutton, who holds a position of secrecy and importance in a plant which manufactures a new type of antitank gun. I shall return soon."

CHOW settled back, munching a fresh wad of chewing gum. He was startled, a moment later, by the reappearance of Zeng.

"You no findee guy?"

"I found him," Zeng said bitterly. "But he could tell me nothing. An empty poison bottle was in his hand, and he was newly dead."

"Killee himself?"

"There are those who would like the police to think so. But I believe he was murdered."

"You callee copper?"

"There is no time for that now. Drive as swiftly as the wind, Chow. We have another man to interview, one whose name is Morrow, and who labors at a factory engaged in making a secret bombsight for British aircraft. Speed, Chow, speed! Lest our enemies reach this Morrow ahead of us and slay him as they slew Dutton. For Morrow's was the second card missing from Dr. Ernst's file!"

The Mongol sent his limousine roaring ahead. This time their destination was an old residence on Nob Hill converted into small flats. Nor would Chow allow Dr. Zeng to enter alone.

"I go too. If trouble, I fight like 'leventeen devils!"

There was no trouble, however, when they entered the flat occupied by the man whose name was Morrow. Once again death had outraced Dr. Zeng, for the bombsight maker lay sprawled on the rug with a bullet through his brain and a silenced pistol clenched in his stiffening right hand.

Frustrated anger surged in Zeng's heart. Muttering, he noticed a phone across the room, leaped to it and dialed Police Headquarters. In a minute he was connected with Captain Brian Carter. The Homicide official's voice sounded oddly shaken.

"Yes?"

"This is Zeng. Come at once to the address I shall now give you. There has been a murder. Two, in fact."

Within less than a quarter of an hour, Carter came bursting heavily into the room.

"It's too much!" he said harshly. "I'm at the end of my string, Zeng! All these killings, and Ann?"

"What about Ann?" the criminologist asked sharply.

Carter's shoulders sagged in weariness.

"She's vanished. Heaven help me, I'm afraid she's been kidnapped!"

Dusk had fallen like a stormy mantle over San Francisco when Captain Brian Carter finally turned the details of the two new homicides over to his departmental subordinates. Then, harassed and haggard, he consented to accompany Zeng to the House of a Thousand Beatitudes for a conference.

They entered by means of the secret underground passageway and ascended to Dr. Zeng's sumptuous living quarters on the second floor. First making sure the window drapes were tightly closed, Zeng switched on the lights.

"It is now a matter of reviewing what we know," he announced, "and awaiting a message."

"What message?" Carter's tone was dull, tired.

"The message from Ann's abductors," the criminologist answered, without visible emotion. "I feel certain that they will contact me."

"How do you figure that?" Carter's eyes narrowed.

"Because I have the solution to this entire chain of mysteries, beginning with the apparent suicide of Steve McCune and including the murder of Dr. Tremayne, as well as the deaths of those two war-industry workers whose bodies I discovered."

The Homicide captain stared.

"In heaven's name, Zeng, tell me what you know!"

Outside the house, a sudden hissing began. That was the rain, falling at last, drenching the city in an abrupt torrential deluge. Zeng Tse-Lin paced as he talked.

"We shall start with Steve McCune, who was found hanged to an attic rafter. That, my friend, was murder, not suicide."

"I won't argue the point with you," said the Homicide official wearily. "Go ahead."

ZENG bowed politely. "Steve McCune was on the swing shift of a shipyard in charge of blueprints for a new type Q-boat. Recently he had become morose, ever since receiving medical treatment from a certain clinic for war-industry workers."

"Okay."

"The F.B.I. suspected Steve of selling those Q-boat plans to Axis spies. In an attempt to arrest him, two Federal agents were slain. Steve did not shoot them, however. I made a paraffin test of his hands, after his own corpse was taken to the morgue. That test showed negative."

"The devil you say!"

Zeng nodded. "I believe Steve really was involved with enemy spies. The spies murdered the F.B.I. men to prevent Steve's arrest. They then killed Steve himself, because he was no longer useful."

"But who are the spies?"

"I am coming to that," the criminologist answered. "I interested myself in the case and, at the request of young Don McCune, began investigation. Since Steve McCune's character had changed after he was treated for a cold at the medical clinic, I decided to look into that clinic. I met its staff, and in the dispensary of one doctor named Max Ernst I found a bottle of scopolamine."

Carter scowled. "Scopolamine? Truth serum?"

"Correct."

"But why would a clinic have that stuff?"

"Precisely the question I asked myself. Before I found a possible answer, an effort was made to kidnap me. The men involved were clinic employees. One escaped. I captured the other, an orderly name Lester. I imprisoned him in my basement, but before I could question him, a shot was fired through the window. It killed him. His body is downstairs now. Forgive me for not reporting it, my friend. I had my reasons."

The Homicide captain looked dazed, as he swore fervently.

"Meanwhile," Zeng went on, "Dr. Tremayne, the clinic's chief surgeon, was stabbed to death and you arrested young Don McCune for the crime. But I feel sure Don is innocent. I think Tremayne discovered that some of his staff members were Axis agents and they murdered him before he could talk."

"The clinic is the center of this whole plot, then?"

"I am sure of it," Dr. Zeng responded without hesitation. "I believe they were using the medical organization as a blind which cloaked their real activities. It was more than a blind, in fact. It was the means whereby they obtained information concerning new American secret weapons."

"By bribing key men like Steve McCune?"

The tall criminologist shook his head.

"Steve McCune was too loyal to accept Nazi pay for naval secrets. I think he was an innocent victim of treachery. So were those other men I found dead this afternoon?Dutton, who worked in a plant that manufactured an antitank gun, and Morrow, who knew the secret of an aircraft bombsight. They gave vital plans to Axis spies, yes; but not voluntarily."

"I don't get it." Carter looked baffled.

"The answer is scopolamine," Zeng said grimly. "You are aware, my friend, that various law- enforcement agencies have employed the drug experimentally to extract the truth from suspected criminals. Under its sedative-hypnotic influence, a man is incapable of telling lies. He answers truthfully to any question asked him."

"You mean?"

Dr. Zeng nodded. "If you were a crook, and someone knew something you wished to learn, would it not be an easy matter to use this truth serum on your victim and then grill him? Especially if you were a clinic doctor pretending to treat a patient for a cold or some similar minor ailment?"

"Good heavens!" Carter muttered. "So that's it! These spies established the clinic for war workers. They chose key men in the various armament industries, injected them with scopolamine and pried military secrets out of them!"

"Quite so. One injection would be sufficient. After a victim had once revealed armament information, he was helpless. The enemy agents could then demand additional data at any time on a basis of blackmail. The war worker would live under a constant threat of having his first act of treachery exposed to the F.B.I. unless he continued to reveal military and naval secrets. That is why Steve McCune's character changed. He knew he had involuntarily betrayed his country, and he feared exposure. When his usefulness ended he was murdered. Today, Morrow and Dutton were likewise slain because my own investigation might lead to them, and the spies were afraid I would make them tell what had happened."

THE Homicide official reached for the telephone. "We've got to notify the Department of Justice!

We?"

"No!" Zeng stopped him sharply. "You are forgetting Ann."

"How can I forget her? She's my only living relative. I think of her as I would my own daughter. But what has she to do with the espionage setup?"

Hawk-like eyes glittering, Zeng Tse-Lin clenched his fists. A bitter vengefulness tinctured his tone as he said:

"Ann means even more to me than she does to you, old friend. And I think these Nazi rats must have learned that fact, perhaps by tapping my phone. In consequence, they kidnapped her, hoping to silence me by using her as a pawn in the game."

"You believe they'll try to strike a bargain? Her safety in exchange for?"

"In exchange for my life," Zeng answered quietly. "They realize I know too much. Now they are gambling on my regard for Ann. It is simply that they seek to lure me into sacrificing myself to save her. Well, I shall play their game."

"You'll risk yourself for Ann's sake?"

"Yes, although I shall have a card up my sleeve. It's an ace which may still win the battle against this master spy who seeks time to cover his tracks and escape."

"But who is he?" Carter erupted savagely.

The criminologist was on the verge of speaking the name of the man he suspected, but at that instant the telephone rang harshly in the room's silence. Long expected and impatiently awaited, the enemy's challenge had come at last.

"Dr. Zeng?" a guarded voice came over the wire.

"Yes."

"Know who this is?"

"I have an idea."

The voice chuckled sardonically. "Very clever. Almost as clever as your smoke bomb at the clinic this afternoon. You didn't learn much, though, did you?"

"I learned enough," Zeng said woodenly.

"And how much have you told the police?"

"Nothing." The criminologist lied for a purpose. "I did not dare, since you have Miss Ann Carter as hostage. Nobody knows the results of my investigation except myself and my servitor, Chow."

"It's a good thing. You probably realize the girl's life won't be worth a plugged pfennig if you talk."

"I do realize it," Zeng assented. "I also realize that you wish to offer a trade. You will release Miss Carter only if I give myself into your hands."

Again the voice chuckled. "You and Chow, yes. Are you willing to deal? Excellent. Here are your instructions. . . ."

It took much persuasion to convince Captain Brian Carter that he must not interfere in the forthcoming showdown. As soon as Zeng had finished listening to those telephonic commands, Carter wanted to contact his Homicide Department subordinates and have the criminologist shadowed to the appointed meeting place.

Dr. Zeng refused this offer.

"Ann's life hinges upon my own discretion now, old friend," he said. "If your men follow me, the entire structure of my scheme will collapse. You must leave now, through that secret passageway by which I brought you here. Henceforward, the fight is my responsibility."

With grumbling reluctance, the police official finally departed. Then, with lightning speed, Zeng Tse-Lin raced up to his third floor laboratory and filled a hypodermic needle with a clear solution. The syringe, of his own special design, he then fitted into one of Lai Hu Chow's artificial legs by means of a swiftly contrived holding apparatus controlled by a small, powerful spring.

Next, Chow detached the false limb he was wearing, and substituted the one with the hypodermic. As he strapped the contrivance in place, his robe-clad master gave him terse orders.

Vigorously chewing a wad of gum, the giant nodded blandly and a smile of anticipation spread across his hatchet-scarred, moon-like countenance.

"Me catchee," he said.

Then he and Dr. Zeng went quietly down to the basement beneath the Mandarin Emporium and made their exit through a deep underground tunnel.

CHAPTER IX
NAZI'S FINISH

BEFORE Pearl Harbor, many of Chinatown's shops had actually been owned and operated by Japs, their merchandise shoddy and cheap in comparison to the goods purveyed by reputable Chinese. After the cowardly Nip attack on Honolulu, however, all Japanese were removed from the mainland's West Coast and relocated in resettlement centers far from the coastal defense zone. In consequence, many former Jap-operated stores in San Francisco now stood vacant and shuttered, empty of wares.

Over the telephone, that guarded voice had instructed Dr. Zeng to present himself at one of these deserted shops. The address had been twice repeated, together with an admonition of sinister insistence.

"Don't bring anybody with you except your big Chinese pal, understand? Otherwise the Carter girl dies."

Zeng had promised, and he was living up to his word. However, nothing had been said concerning the route he should travel, so he approached his rendezvous with Destiny by a path no enemy would have suspected. In brief, knowing the location of the former Jap store, the criminologist chose to reach it underground!

With the mazes of subterranean tunnels beneath Chinatown, Zeng was as familiar as a tiger in its home cave. Needing no flashlight to guide him, he pressed silently onward through a bewildering series of passages, pausing only occasionally to allow Lai Hu Chow to catch up with him. Before three minutes had passed, the giant Mongol was hopelessly lost.

"Blind like fool bat in coalee holee!" he complained in a whisper.

But Zeng merely hushed him and steered him forward.

Presently Zeng's unerring instinct brought them to a steeply tilted ladder, which they ascended to a trapdoor. Opening this without the slightest sound, the criminologist emerged into a vacant store and hauled Chow after him.

A musty smell pervaded the place, and in the dim light from a flickering candle they beheld vast reaches of empty shelves and disused, dusty counters. The candle was on one of these counters, and directly under it there was a chair.

A man sat in that chair, motionless, facing the storefront as if watching. He was pudgy, bald, his eyes curiously glassy. Chow took one look and whispered:

"Jumpee jiminy?is fat doctor flom clinic!"

The giant Mongol was right. There could be no mistaking the rotund form and amiable features of Dr. Max Ernst, who had been the physician in attendance upon Steve McCune, Dutton and Morrow?all of whom had since been murdered. Even though Ernst was silent now, it was easy to imagine hearing his thick, guttural Teutonic accent.

Chow crouched. "So he is head of spy ring! I twist his neck likee pretzel!"

"No!" Zeng Tse-Lin clutched his servitor. "Even you, O Large One, cannot kill a man already dead. Do you not behold the stab wound between his shoulder blades?"

"Me great big dope. Need glasses for bum eyesight. Who killee this guy?"

"That is what I hope soon to learn."

As he spoke, Zeng moved toward the front door of the store. Outside, a figure could be seen standing in the entrance, hunched against the driving rain. Unquestionably it was one of the Axis espionage mob, waiting for Dr. Zeng and his huge servant to come along the street. The fellow had a surprise due him, for his expected visitors were already inside the building!

CALMLY Zeng opened the door from within.

"Were you looking for me, by any chance?" he purred.

The man twitched spasmodically, rasped an oath, and pivoted. A Luger automatic appeared in his fist as if by magic, and stunned amazement marred his pitted countenance. He was Pock-Face, the driver of the limousine which had been employed for that unsuccessful effort to kidnap Dr. Zeng.

"How'd you get in here?" he gasped. "Freeze before I blast you!"

Zeng lifted his hands obediently and gestured Chow to do the same.

"We are unarmed, sir. You need have no fear of us. I entered by a secret way."

"I don't get it!" Pock-Face backed his two captives into the rear of the vacant shop. "You could have got the drop on me, but you passed it up. You could have?"

The criminologist smiled bleakly. "It would have done me no good. By coming here through a hidden passage, I hoped to catch your master napping, hoped to rescue Miss Carter. Unfortunately, she is not in sight. Therefore this is not your real hideout. It is but a blind, a place where I was to surrender myself. As soon as I realized that fact, I knew I must give myself into your waiting hands."

"Yeah," Pock-Face growled. "And you made a wise move."

"Wiser, apparently, than one made by the unfortunate Dr. Ernst." Zeng's gaze went toward the pudgy physician's corpse on the chair.

Pock-Face scowled. "He got nosy. That's what happens to guys who get nosy. Keep that in mind if you want to stay alive a while longer."

"I shall heed your sage advice, sir. And now, if you will conduct me to your employer?"

The gunman sidled to a wall lined with shelves, touched a hidden control and caused an entire section to swing outward on oiled hinges. An aperture was revealed, a secret entrance into the building next door.

The guide gestured Zeng and Chow to walk ahead. He prodded them into an adjoining room which was brightly lighted by an unshaded, dangling incandescent.

In a far corner lay Ann Carter, tied hand and foot, a gag in her mouth and fear in her lovely eyes. The fear turned to hopeless dismay when she saw Dr. Zeng and his giant companion being thrust into view, and realized that they were prisoners like herself.

She was guarded by a thuggish individual who held a Luger in his fist, matching the weapon brandished by Pock-Face. Across the room stood a third man who wore a black silk mask which covered his face from forehead to chin, with slits through which his glittering eyes shone maliciously.

"So you really walked into my trap," he greeted Zeng Tse-Lin in a sardonic, mocking voice.

The criminologist bowed. "I had no alternatives, Mr. George Hartman."

A rasping curse ripped from the masked man's lips.

"You smart Chinese punk!" he snarled, lunging at Zeng. "So you know me, eh?" And he doubled a fist, slugged it home to the mouth of the doctor with the hawk-like countenance.

Zeng made no motion to protect himself. But Chow, when he saw blood dribbling down his employer's ascetic face, seemed to go berserk. Squealing a wild Mongol war-cry, the giant lashed out with his artificial leg and kicked at the Nazi agent's shins.

"Asiatic swine!" Hartman yelped as if he had been stuck by a needle.

HE SWUNG on Chow and dealt him a ferocious punch full to the jaw. Chow didn't even blink. Hitting him with knuckles was like striking a rock with a feather. He merely glared. Then, oddly enough, he broke into gargantuan laughter, a merriment that seemed to come from the inner knowledge of some vast secret jest.

Hartman ripped away his black silk mask.

"No need for that anymore, since you've guessed my identity," he said, and leered at Dr. Zeng.

No longer did he resemble an affable business manager conducting the financial affairs of a clinic. Even his nose looked less bulbous, and there was no brandy on his breath now. Simple though those disguises had been, when he dropped them his entire personality changed. He emerged in his true character of a Prussian spy, a Junkers militarist, a Nazi fanatic.

"How did you guess me?" he demanded of Zeng.

The criminologist shrugged. "Several things gave you away. Let us call it a process of elimination. The spy master had to be an official of the war workers' clinic. It could not have been the chief surgeon, Tremayne, because he was murdered. That also applies to Dr. Max Ernst, whose corpse is even now in the adjoining vacant store. There was only one other physician?Dr. Barton Barryman. And your own error removed him from consideration."

"My error?"

"Yes. The scopolamine bottle, which you labeled 'Fluid Extract of Ergot.' That was a mistake which no medical man would have made. Scopolamine crystals do not resemble ergot. Anyone inspecting the dispensary shelves would have noticed the discrepancy at once. Moreover, there is no chemical formula for ergot yet?you placed a fake formula on the label. And finally, you marked it 'Fluid Extract' but there is no such thing, since ergot is not an exact compound, but varies in manufacture."

Hartman frowned. "I understand. Since no doctor would have used such an obviously spurious label, you assumed that it was done by a non-medical official of the clinic. I was the only man answering that description."

"Quite so, sir."

"You're shrewd," the Nazi granted. "But not shrewd enough. Do you think I intend to release Miss Carter, now that she knows my identity? Do you think you can buy her life with your own?"

"Frankly, no," Zeng admitted calmly. "You never intended to free her. You used her as bait to lure me here, and now you plan to murder us all. Is that not true?"

"It is exactly true!" Hartman grunted.

Dr. Zeng smiled at him, curiously.

"Before you liquidate us, I want you to tell me something. These henchmen of yours?this pock- faced fellow, and the other one whom I have never met before. What do you intend to do with them when you are ready to make your escape from San Francisco?"

A strange expression contorted George Hartman's face, as if he desperately wanted to give a certain answer but found it impossible to utter.

"Why, I'm going to kill them, of course," he blurted in a choked voice. "They are no longer necessary to me. My work is finished here. I shall shoot them down, precisely as I shall shoot you and your servant and the girl."

Pock-Face stiffened when he heard this. So did the other man with a Luger, the one guarding Ann Carter. Pock-Face stared at Hartman.

"Are you kidding, Chief?"

IT was Dr. Zeng who said calmly: "He is telling you the full truth, my misguided friend. You see, Chow had a hypodermic needle full of scopolamine in his artificial leg. The syringe was controlled by a spring. When Chow kicked Hartman a moment ago, he injected the truth serum in your master's ankle."

Pock-Face glared. "So, Hartman! You intend to bump me before you leave, eh? Me and Kroger, here." He indicated his companion in villainy.

"Yes," Hartman's lips formed the word despite his struggles to remain silent. The losing battle he waged against the truth injection brought beads of perspiration to his brow. "I am going to kill you. I don't want you to know it. . . . Herr Gott, what am I saying?"

As he gasped the involuntary admission he

pulled a gun. But Pock-Face was already triggering his Luger. The room suddenly roared with a thunder of exploding cordite and reeked with the fumes of those explosions. As swiftly as thought, Zeng Tse-Lin hurled himself toward the corner where Ann lay bound, shielded her with his own body against ricocheting slugs.

Hartman staggered under the impact of bullets from the Luger which Pock-Face aimed at him. As he went down, he got his own weapon into action. He fired, missed Pock-Face, and hit the other man, Kroger, full between the eyes. Kroger dropped in his tracks, dead before he slumped to the floor.

Pock-Face emptied his automatic at Hartman, and Hartman fell backward, moaning, his belly riddled. Then Lai Hu Chow, yelling like a fiend, grabbed Kroger's gun, lunged at Pock-Face, and bludgeoned him over the skull.

The sound of that concussion was sickening. Pock-Face lurched, swayed drunkenly, sagged. Chow blinked at him.

"Him got eggshell head," the Mongol mourned sadly. "Crush to pulpee with first smack. Chow never have no fun!"

Zeng Tse-Lin was not listening to his huge servitor's plaint. The criminologist was too busy unfastening Ann Carter's fetters, tenderly lifting her upright.

"Are you all right, Ann? Did these unspeakable rats harm you?"

She made a wry mouth as if still tasting the gag that had been between her lips. Then, gently, she smiled.

"Hold me, Zeng," she whispered. "Hold me closely. Then I'll know everything's—as it should be!"

His arms enfolded her, for it is written that the embrace of a loved one is more precious than an emperor's ransom. And who was Zeng Tse-Lin to contradict the wisdom of the ancient sages?