LOCKED CITY

By Thorton Ayre

Exiled from Earth, and facing certain
death, they found the Metropolis of Mars
deserted, except for 7 strange characters

CHAPTER I
Sentence of Death

"RODNEY CALAB, Eva Calab, and Boris Rengard—you stand accused and convicted before this court as traitors to the cause of world progress—as defeated leaders in an effort to overthrow world government..."

The cold, impartial voice of Baxter Holroyd became silent for a moment. Every eye in the packed Hall of Judicature turned to where he sat—a grossly fat, vulgar, bald headed man, half leaning on his high and solitary desk, his pale eyes fixed in gloating triumph on the three in the dock before him.

This was no normal trial, no matter of espionage, but the final act of ruthless injustice that spelled doom for the vast, downtrodden bands of Earth who had seen in the vigorous, intelligent Rodney Calab a new savior from oppression.

Democracy, fascism, communism... Together with hundreds of other distinct policies they were all merged into a common dust in a record of nearly fifty years of desperate slaughter and struggle. First Europe and Great Britain; then the United States (with her isolation scheme in pieces) sank too. Japan and Russia rolled into the whirlpool. Across the world raged war at its vilest. Democracy and liberty were swept out of all knowledge. Iron dictatorship had won.

For ten years now, Baxter Holroyd, better known as the Iron Dictator, controlled the Earth's peoples with a severity and cruelty that bad no parallel with the past. Science went on, cities were rebuilt, civilization picked itself up again—but all for the good of Holroyd. Anybody daring to raise a finger against him or his retinue knew the answer was always instant death.

Rod Calab and his wife, Eva, defied that possibility. Together, with the young chemist Boris Rengard to help them, they struggled desperately and in secret to devise ways and means of scientifically undermining Holroyd's power; were within an ace of success. Then came exposure, trial, and now—

"There are various means this court could adopt to dispose of you," Holroyd resumed smoothly. "You could be shot, you could be burned slowly with heat rays, you could be exiled to the new Polar continents... All those things we could do, but we shall not.

"Today, in this proud year of 1990 it is science that definitely holds sway, that bows down before the rule I have instituted for the common good of the people. To the end of furthering that science you shall be given a chance to live..."

The three remained silent—Calab, tall, lean limbed, dark haired, with a resolute jaw; his wife upright and defiant, blonde headed and blue eyed. Both of them moved only slightly. Boris Rengard did not even do that. Small and lofty browed, unruly hair as red as a sunset and eyes so dark they seemed to have no pupils, he stood gripping the rail in front of him, knuckles white through the taut skin of lean hands. Whether facing death or life science was his only stimulus. He waited expectantly, almost coolly, staring up into the grinning, flabby face looming above.

"Yes, a chance for life," Holroyd repeated softly, but it was a softness that had the bitterness of nitric acid. "You may be aware—you in particular, Rengard—that our science now is faced by two major problems, atomic force and the feasibility of space travel. I say 'feasibility' because space travel by rocket ship is an accomplished fact.

"The work of Calva Neil, your close ally in your attempt to overthrow me and whose life I now spare only because of his genius, has unlocked the void for us. But where are there lives we can sacrifice in the first experimental trip across such a vast gulf as, say, forty million miles? Criminals are too useful; ordinary citizens too valuable.

"That the journey can be made, we know full well, but the strain on a human frame has yet to be ascertained. No man has ever yet been into space.... You three will make the initial journey!"

A heavy silence dropped on the hall as the Dictator mused for a moment, rustled his papers.

"The chosen objective," he resumed, "is Mars. Principally because it is obviously a dead world; also because its conjunction is favorable at the moment; and again because a forty million mile journey will tell us all we need to know if a longer trip is ever attempted.

"You, three will be rendered unconscious for a period of two weeks. During that time the rocket ship carrying you will cross the gulf, controlled as on previous occasions by the Neil Remote System. I need hardly add that, in view of his recent collusion with you, Neil will be heavily guarded during the process.

"It is certain you will land on Mars without mishap. If you have succumbed to the strain you will obviously be dead. If you have survived you will awaken. When you do that, certain concealed micro-waves networked across the interior of your cabin will react on photoelectric cells as your bodies intercept their paths. The cells will in turn actuate along a remote controlled beam and-produce a response back here on Earth.

"We shall know by that means that you are alive—that space travel can be accomplished by human beings. Because you do not know the position of these beams, because you will be too dazed on recovery to even bother thinking about them, you will be quite unable to prevent the signals going forth. Is that clear?"

"And if we do live?" asked Rengard stonily.

The Dictator smiled icily. "Then, my friends, Mars is all yours!" he grinned. "A mostly waterless, airless planet to do with as you will. It is one world we shall never trouble to colonize, but if you can reach it, it makes us secure when we decide to take over Venus and other possible worlds. Then outwards—to the Galaxies!" Holroyd paused, oozing for a moment that spell binding power that had made him the ruler of a harassed, post-war world.

"Your ship will have enough fuel to reach Mars—no more," he resumed. "You will have no provisions, and no water. If you do awake, you will soon die... horribly, as you deserve—"

In the jammed hall outside came a commotion.

"I won't do it! Damn you, Holroyd, I won't!"

The Dictator and three in the dock turned. In an instant they recognized the blond head and ruddy-cheeked face of Neil, their defeated friend, perhaps one of the cleverest young electrigeniuses of the age. He shook his fist savagely across the astonished mob of people.

"I'll not guide any ship containing my friends!" he roared. "They are my friends, always will be, and no radio control of mine is going to send them to such a death as that!"

"No?" Holroyd's thick lips were sneering. "We will see to that later, my friend. Guards, take him away! Hold him under strict observation until further orders. Take these three prisoners away too. Sentence is passed!"

He leaned back and watched complacently the prompt execution of his commands.

Just after sundown he was watching again, from his apartment window in the Executive Building, the departure of a rocket ship climbing in a streak of sparks to the cloudy sky. Languidly he turned to the televisor and switched it on. It gave him a picture of the remote control radio room in another quarter of the vast Executive Building.

Young Calva Neil was hunched over the controls of his amazing apparatus. Every moment was clearly one of extreme helpless bitterness. Time and again he looked up at the iron-faced guards around him with their leveled ray guns . . . then with a hopeless shrug of his shoulders turned back to his task.

Baxter Holroyd switched off, and smiled-the smile of a being who has more of the snake in him than the man.

CHAPTER II
The Deserted City

ROD CALAB moved dully, heavy headed, aching. His body throbbed as though it had been subjected to an interminable succession of hammer blows. Wearily he opened his eyes, found himself gazing at a roof of curved metal illumined by weak reflected sunshine.

Little by little remembrance seeped back—the anesthesia. on Earth in the prison cell, the memory of a last helpless struggle. The journey to Mars? Forgetful of his pains he eased off, the soft spring bed against the wall—eased rather too rapidly indeed for the lesser gravitation instantly made itself evident and sent him sprawling.

After a minute's careful effort he found just how much energy he needed. Gently he picked his way to Eva and Rengard as they lay motionless on their beds, eyes closed, faces white and rigid. Anxiously he felt their pulses. They were still alive, sluggishly so in the grip of unconsciousness. There was nothing could be done for them but wait for the awakening.

His head clearing a little Rod stumbled to the window, clutched the frame and stared outside. It was a view that brought hopelessness into his gray eyes. The vessel had landed in the midst of a near-horizoned desert. It stretched away, uneven and bumpy, totally empty of life. Overhead the sky was blue black, powdered with brightly gleaming stars, the green spot of Earth itself visible low down in the west-— or what Rod judged to be the west.

"Grand place to have a thirst!" he whispered, licking his dry lips. The stimulus shot into him at the time of the anesthetic had kept his body nourished during the two weeks, but now he felt the ravaging pangs of thirst and hunger. Wearily he rubbed his aching head. Then he turned about and looked at the fuel gauge.

There was still some explosive in the chambers—about enough to cover 2,000 miles. No more. Return to Earth was an absolute impossibility. With fingers that ached he operated the external air devices, made a wry face at the readings. The atmosphere outside was unbreathable in its thinness, approximating that of Earth's stratosphere.

"Damned lousy place!" he growled bitterly, and licked his lips again.

"I agree with you, Rod."

He turned in swift surprise and found Rengard sitting up on his bed, his red head in his hands. Savagely he ruffled his flaming locks, then looked up with a faint grin.

"Well, we made it," he commented. "Guess Holroyd's aware of it by now, too. Our alarm signal will have reacted, I suppose. Not that it does us much good, of course," he finished moodily.

He tested his weight against the gravity, moved to Rod's side and sourly studied the instruments. Then, shrugging, he flung wide the doors of the storage cabinet and gazed at the empty shelves with bitter eyes.

"Nice going!" he sighed. "Holroyd certainly kept his word. If we're to get out of this hole we've plenty of fast thinking to do."

"There isn't a way out," Rod growled. "Holroyd knew that when he sent us here. We're just prize guinea pigs, that's all."

He turned aside at a low cry from Eva. Gently he supported her as she began to recover consciousness. In ten minutes she was fully awake, in possession of the cheerless facts.

"Wonderful!" she shrugged; then with a whimsical smile, "What a pity space didn't make an end of us. Not much sense in being wakened up to die, is there?" She turned and looked at Rengard. He was standing by the window now, hands deep in pockets. "Any ideas, Ren?" she asked. "You're usually the one to get 'em."

"Maybe I have," he mused. "Come here a moment...."

When they had come to his side he pointed across the desert towards the horizon. "Notice anything out there, against the sunlight?" he asked quietly.

"You mean that tremoring effect against the light?" Rod questioned, staring steadily. "Looks to me as though it's coming out of the ground—"

"Yeah; and if it is it means warmth," Rengard pointed out. "It would rise rapidly in this thin air. Warmth from inside the planet might mean anything. Might as well go and see what it is. We've fuel enough for two thousand miles, so let's go...."

He turned actively to the switchboard, remembered the gravity and shuffled forward slowly. In a moment or two he had disconnected the automatic radio devices and flung in the main power switches. Instantly the tubes fired, drove the ship upward in a cloud of dust and sandgrains. Against the lesser gravity it moved with consummate ease.

Rod and the girl remained at the window, holding onto its frame. The terrific speed of the vessel and the slight attraction played the oddest tricks on their sense of balance.

"Why, it's—it's a dead canal junction!" Eva cried suddenly, pointing below to the skimming desert. "Or is it?" she frowned. "Looks like a pit of some sort...."

Rengard stared into his own observation window, took in a view of five dead channels, which had obviously been canal systems at some remote period, all running into a common convergence in a vastly deep, sunken circle. It took him a few minutes to realize that he was actually gazing at a shaft—that the darkness of the hole was not caused by the black shadows of the desert, rendered intensely dark by lack of diffusing air, but by tremendous depth going down heaven knew how far.

"Warm air out of that, huh?" he murmured. "That's interesting! You two ready to take a chance?" He glanced across the room.

"If you mean to go down the mine—yes," Eva said, seeing Rod's look of agreement. "Guess we can't be any the worse off, and we might find a lemonade or hot dog stand somewhere below. Go to it!"

"Oke!"

Rengard slammed in more switches, ?ew round in a sweeping semicircle, then tilted into a dive that sent the vessel whizzing downward with breath taking speed. For an instant Rod and Eva cramped their eyes shut; it seemed a certainty they were going to crash into the shaft's side; the gravity was so light it was hard to control the machine properly....

But Rengard knew what he was about. With a dexterous swing and a roar of exhaust he plunged into the abysmal dark of the place, slowed the speed, found the shaft wide enough to carry the ship broadside and so teetered down little by little with his ground blasts belching below to prevent a sudden fall.

With anxious eyes he watched the throwback meter—an instrument designed to show exactly how far away the ground was. He stared unbelievingly.

"Thirty miles!" he gasped. "A shaft thirty miles deep! It isn't possible...!"

But he was wrong there. The shaft was all the instrument claimed it to be. The ship descended in jerks for nearly an hour before it finally burst out of the eye-crushing blackness into a titanic, brilliantly lighted expanse that jolted the retinae with its sudden effulgence.

The three stared out on the amazing emptiness. Apparently it was chiseled smoothly by unguessable forces out of sheer virgin rock. A cavern, of stupefying size, illuminated at opposite ends by two blindingly brilliant balls, their heat becoming evident on the meter registers, but not through the proofed windows and walls.

"Energy, I'd say," Rengard murmured, fingering his controls. "Energy cores of some kind, slowly eating their way through the rocks perhaps. Probably the original forces that started this cavern going. Maybe natural, maybe man made, I don't know—"

"Civilization!" yelled Eva suddenly, interrupting him. "Look down there!"

She pointed excitedly below. Rengard and Rod stared with her, down upon the amazing sight of a solid, invincible looking metropolis, " its topmost heights reaching nearly to the cavern roof. In all it covered several square miles.

The buildings were of bluish metal, almost like chromium in their odd tint, perfectly architectured and studded with gleaming windows. The streets were orderly and spacious, the squares broad and imposing. There were pedestrian ways, traffic ways, monorails, subway entrances, every conceivable adjunct of a highly advanced city, and yet--

Not a thing moved! The place was utterly empty and deserted!

"Odd," Rengard muttered, staring over the silence. "Damned odd! Looks as though everybody's gone for a holiday...."

He looked beyond the immediate city and found it was almost surrounded by a small jungle, in the midst of which were splashes of yellow which revealed themselves into fruit trees as the vessel dropped lower. Fruit like melons. In between the trees was the gleam of water in the twin sunlight.

"Water!" Eva gasped thankfully. "Thank heaven for that!"

"If it's drinkable," Rengard said pessimistically, and hardly dared glance at the instruments. Then he said brightly, "We're in luck. Air pressure down here is about the same as Earth's. Only explanation is that the Martians, if any, trapped it down here when things got too thin on the surface. Surface air now represents the equivalent of our stratophere...."

He brought the ship down in a little clearing, facing a miniature lake lined with the heavy trees. It was shadier here, hidden from the glare of the suns.

Rod turned to the airlock, unfastened the heavy screws and flung the cover wide. The air that entered was hot and moist, but otherwise little different from Earth's.

Almost instantly Rengard vaulted like a kangaroo through the opening and headed in flying leaps towards the pool, flung himself down on the mossy ground and plunged his face into the shining coolness. He drank noisily. For a scientist he was amazingly lax in making no preliminary tests; but then thirst had overcome all prudence. He straightened up at last and wiped his trickling chin.

"Swell!" he observed, sighing contentedly, as Rod and Eva looked down questionably upon him. "Try it!"

They lay on their faces to follow his example, but before their lips touched the water they looked up sharply as Rengard gave a hoarse cry.

"For Pete's sake, look!"

Slowly they stood up again, staring amazedly at the first evidence of life they had so far seen. Surprising life indeed!

Little creatures, so human in form it was hard to distinguish them from Earthlings, save for their blue tinted skin and large vividly blue eyes, were moving timidly from out of the shadows of the trees. In all there were seven of them, clad in loose, sleeveless garments that reached to their knees. Their hair, the color of ripe corn, flowed in bushes round their heads, caught up in some cases with a blue band, but in others left to flow wild.

Rod stared at them, blinked as he saw that in their slim-fingered hands they held the melon fruits, extended forward as though in the form of a gracious offering. The feet of the little creatures, encased in soft, vegetable like shoes, made hardly any sound on the mossy turf.

"Why, they're—they're only kids!" Rengard cried. "They're not even fully developed yet!"

"You're right," whispered Eva unbelievingly.

Certainly the limbs of the little people were quite childlike. The arms and legs lacked all signs of maturity; they were lissom and supple, free from all sinew. From the difference in form of three of them, and the bangles on the hair, it was pretty obvious that three were girls, and the remaining four boys.

"Say, is this a Martian kindergarten, or what?" Rod whistled. "I don't begin to—"

He broke off as one of the girls held out her fruit more boldly, jabbed a rounded arm towards the pool. "Juzaf!" she observed, making a pained grimace and rubbing the region of her stomach. "Ulfa juzaf!" She thrust the fruit out again.

The rest of the children nodded seriously at her remark and Rod scratched his head.

"The pool," he said, taking the fruit, "is ulfa juzaf—whatever the hell that is."

"Yeah...."' Rengard looked serious. "Wish I knew what it meant. Tasted all right to me."

Pulling out his knife, Rod cut into the fruit vigorously. The juice instantly began to stream out and he held it over his mouth. Appreciatively he drained it.

"Gosh!" he whistled. "Melon, port wine, champagne, and a high ball, concentrated!" He cut the thing into pieces and chewed it gratefully. "Good as beef steak.... Try it. You can't go wrong."

The children looked on in pleased interest as Eva and Rengard took the rest of the fruits and made an attack on them. The stuff was surprisingly satisfying, appearing to have tremendously nourishing properties.

"There's something wrong here, all the same," Rod commented, when he had made an end of eating and put his knife away. "These kids, on earth, wouldn't be fixed at more than ten years old. What are they doing so far from the city? May have seen our ship dropping, of course, but even then—"

"Point is," interrupted Rengard thoughtfully, "do they even belong to the city? As we saw it, it was totally deserted..." He turned to the pretty little group and showed them the metropolis through the trees. "City?" he asked. "City yours? You come from there?"

Their blue eyes looked towards it. They smiled to reveal white, even teeth. They even danced a little; nothing more.

"Big white chief's palaver no dice," said Eva solemnly.

Rengard shrugged. "Guess you're right. I'll have to learn their language. Sooner I know what juzaf means the better I'll like it—"

"The language can wait," interrupted Rod briefly. "I'm going to take a look at that city and see what's wrong with it. There must surely be somebody? The parents of these kids, for instance? Let's be looking."

"It's sure got me puzzled too," Eva said thoughtfully. "It stands to reason these kids didn't just 'grow' like Topsy. I'm for finding out now."

CHAPTER III
The Seven Master Locks

THE party headed through the queerly fashioned, fruit-laden trees. The Martian children seemed to regard the whole business as some kind of pleasure jaunt, skipping and jumping along behind the three Earthlings.

The nearer they came to the city the more they were puzzled. The jungle led directly down onto one of the main entrance streets, thence into the city center, yet as they progressed slowly along they saw no signs of anybody. Not a thing moved: the giant metropolis loomed around and above them, the very quintessence of power—with nobody to look after it! There were not even any more children, apparently. The seven who danced and giggled with amusement, watched with wide-eyed innocence, were the only guardians.

For an hour—two hours—the party wandered in and out of the great open buildings, found machines set out in orderly array, machines of such complexity that they defied comprehension. It was pretty obvious that they were electrical, and in perfect condition, their controls all being centered on a massive switchboard.

But there was the funny thing. The master switch was locked! It was fastened around with bars of metal slotted into combination wards that no power could conceivably break—except the knowledge of the actual combination itself.

"Talk about burglar alarms," murmured Rengard. "This city looks like one plus." He looked helplessly at the smiling children, patted the head of the nearest boy in controlled exasperation, then turned about to continue the tour.

Yet everywhere they went, every building they looked in, things were still locked up. In one edifice was a vast army of robots, standing motionless. In another there stood a solitary machine—a gigantic circle of metal, its surface finely filigreed, its entire bulk supported by gracefully arched metal arms. It was not unlike a vast gong. Only a vague idea of its purpose could be gathered from tremendous horseshoe magnets grouped above and around it, which in turn linked up to a baby forest of glass tubes, insulator banks, wire wound drums, and finally by far the biggest switchboard yet. Puzzled, the three moved forward and studied it silently.

It was dominated, amongst a stubble of plugs and buttons, by seven massive switches, all of them combination-locked.

"Looks to me," said Rod slowly, "as though this switchboard is the keyboard to the whole lot. The others we've seen are probably released when this one is. I don't pretend to know how to begin—"

"Look!" breathed Eva suddenly, with a hoarse little gasp.

The urgency in her tone forced Rod and Rengard to twist round. The children gave little cries which were unmistakably of surprise; And there was reason; for lying close to the wall of the huge place was a broken skeleton.

Immediately the Earthlings were beside it. Rengard hovered over it with brooding brows; Rod fingered the dusty bones. Though it had fallen apart with age the skeleton's outline was still distinguishable. It possessed a surprisingly large skull, big chest, spindly legs, had probably been owned by a man seven feet tall.

Rod stroked his chin thoughtfully; Rengard scratched his fiery mop.

"The only remaining evidence of people outside of these children," he breathed, gazing at them as they squatted on their haunches watching the proceedings. "Just what is the inside story on all this, I wonder?"

"Only way to find out is to adopt your method and learn the language," Rod answered briefly.

"Yeah—later on. More exploring to be done yet. Come on."

They left the building slowly, and as usual the children followed them in their journeyings. They examined buildings obviously designed for residence, others for storage, then one that was a masterpiece of telescopic and radio skill. The entire mass of apparatus was quite recognizable—but locked. Still another building was piled to the roof with armaments. There were tens of thousands of searchlight objects that were probably heat rays. Crate upon crate of blue metal contained gray cylinders that looked suspiciously like bombs, but because the lattice tops of the crates were locked there was no way of finding out.

Then in an adjoining hall was something that made the three Earthlings stop dead, catch "in their breath in amazement.

"Gosh! Space ships!" Rengard cried, staring on nearly fifty or so long ovoids, placed in orderly lines on both sides of a narrow gangway. Only for a moment did he stand drinking the scene in, then raced forward to the nearest one, fell back in bitter disappointment before closed airlocks.

"Locked again!" he groaned. "Did you ever see a city with such terrific knowledge and resources so completely fastened? Everything in apple-pie order—Lord knows how much power waiting to be tapped, and we can't do a thing about it."

Tireless with interest they wandered on again, the children chattering their strange language beside them. They went from one end of the city to the other, glimpsed power rooms that housed locked engines of incredible power—and so finally arrived in an immense laboratory. Here again the machines were locked, but the numberless bottles and phials on the shelves were free. Rengard glanced at them, then turned to survey seven small tubes standing in a frame on the floor, tubes which were of some glass composition, shattered now from top to bottom with shards and splinters flung in all directions.

"Seven tubes," he muttered; then a giggling laugh made him swing round impatiently. His expression changed. "Seven tubes—seven children!" he breathed tensely.

"Great Cat, yes!" Rod gasped. "You—you mean you think that these kids perhaps came from these tubes?"

Rengard did not answer immediately. In silence he went round and peered into the phials and jars.

"I'm not so hot on chemistry of Mars, but carbon's the same the universe over," he remarked at length, turning. "These phials and things have carbon in its various forms inside them. Life is impossible without carbon, of course—flesh and blood life, for instance, like these kids and ourselves.

"I believe it isn't impossible for Martian science to have created life—these children—with the machinery we see about us. Possibly the children were born in these tubes, burst them open and stepped out like a bird breaks from its egg, only to find... Only to find themselves alone," he finished, thinking.

"Then why didn't they die?" demanded Eva. "I never heard of a baby looking after itself from the moment of birth."

"Perhaps these weren't ordinary babies," -Rod pointed out.

"More I see of this place, the more I'm reminded of the Mary Celeste," Rengard observed. "I'm starting in right now to learn the language. We'll make our headquarters here and eat fruit. Until we find out what jusaf is I guess we'd better leave that water alone. Juice can take its place."

He turned to the children, motioned them to him. They came forward readily enough, squatted in a circle around him as he sat down on the floor to begin his laborious task.

Picking the things around him as examples, he began—and persisted... And persisted.

In the course of the next few days, reckoned from Rod's watch since day was of course perpetual, strange changes came over Rengard. For one thing he ate three times as much fruit supply as Rod and Eva; he drank juice until it seemed he would never stop. Nor was it entirely explainable by the terrific heat.

Outwardly, too, he was different. He exuded a sense of radiant well being and activity, slept but little, spent endless hours questioning and cross questioning the often sleepy children who now seemed to have come to regard the laboratory as their new home.

Their intelligence was by no means outstanding, and that was why it seemed so extraordinary to Rod and Eva to behold Rengard's mind leaping all the defective gaps. He conducted himself like a genius, hurdling with incredible mental agility from one point to another, piecing together the Martian language in double quick time. The first thing he discovered, to his discomfiture, was that "ulfa juzaf" meant "death liquid," though exactly why he couldn't then determine. Trouble was, the children still had a good deal of baby talk, which rendered his task all the more difficult.

None the less he could speak it haltingly within two weeks. In a month, still giving off an aura of accomplishment and purpose, he was proficient enough to teach Rod and the girl. They found it more difficult, were only assisted in understanding by Rengard's brilliant little touches to bridge the hard gaps.

When he rested from his linguistic activities he roamed the great empty city alone, seemed to arrive at certain conclusions, for on one occasion he remarked,

"It's pretty obvious where the Martians got their power from. Those machine rooms give the answer. The whole planet can be used as a generator. The site of the master plant is directly in line with the Martian north Magnetic Pole. The planet in its revolution against the time-space ether generates power like the armature of a dynamo. That means endless and terrific power, more than sufficient to drive the city's many mechanisms."

"And how do we use it?" Rod asked bitterly. "We still don't know and these kids can't tell us anything even now."

"That's the trouble..." Rengard leaned against a bench and rubbed his brow mystifiedly. The children gathered round him quietly. Again he asked them the question he had so often repeated.

"Where are your parents? How did you get here?"

As usual, the shrugging of slender, blue-tinted shoulders; the frankly innocent looks and giggles.

"The machines!" Rengard persisted. "How do we make them work? Where did the men go that built them?"

"Drinking—much juzaf," answered the pretty little girl who seemed to have appointed herself as leader. "They died."

"Huh?" Rengard looked at her sharply. Catching her hand he drew her to him. "Listen, youngster, I know by now what 'juzaf' means—that it's a death liquid. But why? Can you explain that?"

The child screwed up her face in thought, seemed hard put to it. Then struck with a sudden inspiration she pointed to Regnard's temples. "Juzaf cause that," she said haltingly.

Rengard stared in wonderment, then Rod gave an exclamation:

"Say, Ren, looks like some radiation's getting at you, else you're worrying too much. You're going gray around the temples!"

"So you are!" affirmed Eva wonderingly, pulling a hand mirror from her blouse pocket. "Here, take a look."

Rengard stared at his flaming mop his rosy face and bright eyes. The whole picture reflected back at him was one of almost marvelous good health. But certainly gray hair was creeping along the sides of his head.

"Old age," he growled, handing the mirror back. "Not that it matters anyway."

He pondered for a moment, said slowly, "You know, I'm beginning to get the hang of several of these machines, and yet I don't know exactly why I should. I've had no experience of them. Just the same, something's happened to my mind recently. I'm able to figure out quite a lot of things I couldn't manage before. Notice how easily I learned the Martian language for one thing? It's as though I've suddenly turned into a genius for no particular reason, and-—"

He broke off, stopped dead, clearly struck by a sudden amazing thought.

"Lord!" he breathed. "I wonder...!"

He straightened up suddenly. "You two carry on; I'll be back in a while. I've an experiment to make that may settle this mystery once and for all." He took an empty glass phial from the rack behind him and went out of the laboratory with swift strides. The children went skipping merrily after him.

For several days afterwards Rengard became completely absorbed by mysterious work of his own. Eating ravenously at intervals, swallowing quarts of fruit juice, he essayed but few remarks. His whole concentration seemed to be absorbed.

He worked with phials of water from the lakes and pools in the surrounding jungle, brought all his newly found strange genius to a problem that was entirely his own.

Day by day he was visibly different. The vigor seemed to be going from him. Streaks of gray had passed from his temples to encompass most of his red hair. The taut freshness had gone from his face; it was haggard and curiously worn.

Investigating the city on their own, Rod and Eva felt profound concern for their comrade. They knew something was radically wrong with him—something outside the scope of normalcy.

"Can't be anything in the air," Rod commented. "If it was we'd look the same, and we're both all right."

"Can only be that water he drank," the girl said worriedly. "I think that's what he's analyzing now. Remember that we were interrupted before we drank any—"

"But surely it couldn't produce genius?" Rod meditated over that possibility, then shrugged. "Oh, hell—I give up!"

He stared round the great space ship hangar into which they had come. "If only there was a way to unlock all this," he sighed regretfully. "We thought knowing the language would do it, but I guess we're as far off as ever. A whole nation's resources tied up! Think what we could do to Holroyd if we could get this stuff into action!"

"I know..." the girl said quietly, then tugging a pencil from her pocket she started to check off the inventory she had been making of the city's resources—mainly for her own amusement." "This city sure has everything," she murmured, ticking off her items. "Space machines, robots, syntheticising apparatus, laboratories, radio, telescopes, armaments—"

She broke off in surprised annoyance as the boy beside her suddenly snatched eagerly at her pencil and started to examine it quickly.

"Hey, give that back!" Rod snapped, in the child's own language. "Come here!" He lunged forward, but Eva caught his arm tensely.

"No—wait a minute, Rod. He's never seen a pencil before, remember. He wasn't with us on other occasions. Seems silly for a lead pencil to interest him in such a city as this, but—"

She broke off and tore a leaf out of her notebook, handed it over. "Draw...." she encouraged.

The boy looked at her with his big blue eyes, then with a slow nod squatted on the floor. He thought for a moment then rather haltingly began to draw the clumsy outline of an object that was entirely obscure—at first. Eva stooped and watched intently.

"Look here, is this a drawing lesson, or what?" Rod demanded impatiently. "We'll get nowhere just standing around watching this kid draw. Besides--"

He paused, bent down beside the girl, then with a cry of amazement he snatched the paper up and stared at it.

"See what it is?" he gasped.

Eva shrugged, her blue eyes puzzled. "Looks to me like some kind of pyramid with symbols on it."

"Anything but!" he retorted, and bending down he clutched the child's wrist and jerked him to his feet. "This way!" he snapped, and whirled the surprised youngster out of the building at top speed, Eva following behind with a baffled frown. In five minutes they had gained the room with the central switchboard. Rod stared at the massive panel, then back at the drawing. The girl looked over his shoulder.

. "Why, it's a pretty fair representation of the fifth switch!" she cried. "The symbols in between might pass for combination numbers and— Rod, do you think that—?"

"Listen, kid!" Rod caught the youngster's shoulders earnestly. "Do you know anything about this machine? These switches?"

The child hesitated, then pointed to the fifth switch. Without wasting a moment Rod caught him up in his arms, held him so that his slim fingered hands could touch the profoundly complicated combination lock that held the switch in place.

There was something uncanny about the way those childish hands went in and out of the rings and bars and loops forming the combination matrix—but at last, after five minutes of unerring work there was a sharp click and the lock opened!

"He did it!" Rod gasped blankly. "Well, by all that's incredible! How in the name of wonder—?"

He put the smiling child down and rather hesitantly pushed the switch into place in the lower contact blades—but nothing happened. The machinery in the great room, the forest of tubes, remained motionless.

The girl gave a little shrug. "Obviously one switch alone is no use—all the lot have evidently got to be in circuit before the thing can work. Odd, though, that this kid knew all about that one switch. Unless..." She wheeled round, startled.

"Seven switches—seven children!" she cried hoarsely, eyes wide. "Rod, what fools we've been! It's so obvious. Somehow these children are connected with the board—they're living keys! If this chap knew how to unlock switch Five, it's a cinch the other six in the lab with Ren know the rest between them. Come on, we've got to get them—"

She swung round to head from the building, then stopped in her tracks as Rengard suddenly appeared with the other six children grouped about him. He moved slowly, with obvious effort, clutching the machinery for support as he came forward.

CHAPTER IV
The City ls Unlocked

"REN!" Eva cried in horror. "Whatever's wrong?"

She stared in alarm, with Rod right beside her. The children caught something of their anxiety and their smiles vanished.

For Rengard was an exceedingly old man! His hair had changed to snow white, was even missing places where the baldness of extreme senility showed through. The formerly strong hands were bony and veined; the face sunken and bloodless. Only a slight semblance of the old fire remained in his vividly dark eyes—the eyes of a young mind housed in a tottering frame.

"Well," he whispered, leaning against a machine, and talking in a voice that was thin and reedy, "I've solved part of the mystery, and at the same time discovered how darned right this kid was when she called Martian water a death liquid. I—I haven't long to live, so listen—carefully!"

Rod and the girl supported him gently as he sighed heavily. Silent, timid now, the children congregated in a little knot and watched with wide eyes.

"The—the Martians died because... because of heavy water," Rengard whispered, smiling twistedly with bluish lips.

"Heavy water?" Rod mused, frowning. "Seem to have heard something about that some place—"

"Of course you have. There were—were scientific references to it on Earth a very long time ago. Way back in the early thirties, before the war came..." Rengard took a deep breath. "That water I drank was heavy water. Laboratory tests prove it.

"Well?" breathed Rod tensely.

"I'm—I'm coming to it...." Rengard said heavily, talking again with noticeable effort. "The ponds and lakes down—down here are heavy water.¹

1: Rengard's discovery uncovered the mystery of the Martian race's vanishment. Obviously forced underground by expiring atmosphere on the surface, they constructed canals from the polar caps before they came below. The canals had water pipes leading down to their new home. And thus, perhaps for ages, the race lived below, out of contact with the surface, until even the canals dried up as the pole caps receded still farther. But the water balance in the cavern by that time had been fixed.

But during the ages the atmosphere thinned out, something occurred that the Martians did not suspect. Intense electric radiations from the sun, unhindered by atmosphere, reacted on the canal waters. These radiations, pouring endlessly out of an always clear sky, produced electrolysis in the Martian water. Not all at once, but by gradual changes, so gradual that the Martians never noticed the difference. For that matter, there is hardly anything different in the taste of heavy water, only a slight bitterness.

Heavy water is called such because it has more electrons than normal water. The exact process produced by the solar radiation broke down the water's oxygen and hydrogen and left a residue, an isotope. That isotope is heavy water. Little by little the change spread through the entire water and gave it more electrons than it should normally have.—Ed.

"The Martians, constituted like us to take ordinary water, could—could not cope with heavy water. Instead of them just being stimulated, they were overstimulated. Over stimulation leads to a progressive speeding up of the body's molecular activity. They ate more and were given what seemed.... Were given what seemed to be an extremely good state of health, a—a sharpening of mentality amounting to genius.

"As I see it, with this new found genius they built this amazing city and fixed its machinery, until they suddenly began to discover that it was not anabolism theyhad got, but extreme ketabolism, the breaking down of bodily structure. The—the same thing that's gotten into me through drinking undiluted heavy water when we first arrived.

"The Martians were burning up, living at a furious rate of energy, skipping whole years of their life span, cramming entire masses of knowledge into a short time, until the body, no longer able to resist this telescoped evolution, broke down and plunged them into old age and—and death. You—you understand?"

"Yes—we understand," Rod whispered. "But, Ren, the forest? That grows round heavy water lakes but shows no signs of anything unusual."

"Plants are different," Rengard muttered. "Probably their constitution is such that they can break down the isotope into normal water.... Plants are natural chemical factories, remember; can do things a human body cannot. That's the only way I can explain if."

"And these children?" Eva asked. "They're all right."

"Why not?" Rengard whispered. "They know—don't ask me how—that the water's fatal. They only—only use fruit juice which shows the plants overcome the trouble. I—I haven't solved the mystery of the children, but I'm sure the last Martians suddenly realized, like me, that death was very close and took rapid measures to preserve an achievement they could never possibly use...."

Rengard stopped. His voice had been sinking throughout his last words; now it trailed off altogether. He sighed heavily, slumped from the machine he had been leaning against and collapsed limply on the floor.

In an instant Rod caught him up in his arms, stared down on the waxen, shrunken face. His fingers felt the skinny wrist.

"Dead," he muttered, staring up into Eva's horrified face.

She said nothing; the whole business was too tragically swift for words. The seven children kept silent. It was obvious from their expressions they had no idea what it was all about.

"Nothing we can do except bury him," Rod muttered. "Poor old Ren! He passed out like a true scientist, anyway...."

Slowly he got to his feet, shook off the lethargy of sorrow. "Better give me a hand, Eva. Afterwards we'll see if the rest of these kids know anything about this switchboard. Then maybe we'll solve the rest of the mystery...."

They buried Rengard in the jungle, recited a simple service over his grave with the children around them. Then they returned to the city, had a further meal of fruits, and started anew on their line of discovery.

One by one they tested the children; and one by one it became revealed that each child had a perfect knowledge of one switch. First the boys, then the girls, unfastened the highly intricate combinations as though it were literally child's play. Six of the switches were accordingly closed into contact, but at the unlocking of the seventh one Rod hestitated and glanced uneasily at the girl.

"Ren figured that this entire planet's resources worked by planetary dynamo," he muttered. "What's going to happen if this switchboard starts everything going? We might bring the place. down! It's pretty certain this last switch will make this board start working, then things will begin to happen."

He looked uneasily at the titanic circular disk in the midst of its magnets. It seemed in some way to suggest the very matrix of the whole city's resources.

"After all," Eva said slowly, "we can't be much worse off anyway. If we don't throw that switch we can stick around in this prison of knowledge until we die. Better close it, and trust to luck what happens..."

"O.K." Rod's fingers tightened on the heavy bar. "He tensed himself and held his breath as he closed the copper blades. A little shower of sparks spurted from them. Gingerly he stepped back and looked anxiously around.

A low rumbling was creeping out of the heavy silence. The myriad small machines grouped about the giant metal circle started to hum with sudden power—the ceaseless power of a planet's own electricity generated by its own revolution, passing thereafter throughout the length and breadth of the huge city.

The noise increased, rose to the whining hum of a power house. Heat began to rise on the already stuffy air. The masses of banked tubes filled with luminous life. The horseshoe magnets glowed with somber redness.

The children gave little cries of fright, clung nervously to the grownups. Rod gulped and felt his forehead was wet; Eva shot him an anxious look.

"Wish I knew what was going to happen—what it's all about?" he breathed, staring at the filigreed circle in front of him. "Reminds me of a stone starting an avalanche...."

He became silent again, desperately uneasy. The machines had a fixed note now—a singing throb of power that evidenced perfect engineering, of gears smoothed and lubricated to be almost frictionless. Then above the whining came another sound, of heavy clanking, coming nearer.

Rod swung round, started violently. Two robots entered the great place advancing steadily on their metal feet.

"Hey, wait a minute!" he gasped hoarsely, as they came invincibly forward. "Stop, confound you!"

They stopped dead. Rod stood blinking at them and their lensed eyes stared back, probably photographing every movement he made.

"Say, they—they obeyed!" he stammered, turning. "I just wonder if—"

"I've got an ideal" Eva said suddenly, and swinging round she stared at the great circle of filigree metal, said sharply, "Take four paces to the rear—March!" Then she turned round again and watched with a triumphant smile as the robots faultlessly obeyed her order and halted.

"Voilá!" she cried.

"But how—?" Rod gasped, in wonder. "What makes 'em tick? How do they do it?"

"Just a hunch, and it worked," she answered lightly. "This city, Rod, is a flawless arrangement of machinery, geared to operate not by ordinary hand action but by thought waves! That isn't so unusual; telepathic experts on Earth can accomplish similar feats in an elementary style.... This central thing here with its meshed face is, I'm convinced, a magnetizer. It receives and holds the tiny electrical impulses of thoughts, just like a phonograph record receives notes. In the same way it amplifies the thoughts and radiates them. One thing is obvious. These robots have telepathic pick-ups responding to thought wave stimulus. The language doesn't matter; a telepathic command is the same in any language."

"If you're right, why did only these two come along? What about the rest of them? Why not the whole army?"

"Probably because they have different duties. These two probably respond as servants—not for instance as soldiers, or anything like that. Don't you remember saying you wished you could understand what was going to happen, what it was all about? Well, probably these two can explain and that's why they came. After all, you gave an unintentional order . . ."

"Well I'm damned!" Rod looked puzzled fora moment, then gave a discomfited grin. "Darned uncanny, if you ask me. Beats me how anybody could think up a city as perfect as this one."

"Why not? The Martians were probably far ahead of our science in any case, and when they got genius added to it—Well! There would hardly be anything beyond them.... Rod, we've got a whole city ready to obey us; we've got to act wisely. Here's to seeing what we can find out..."

The girl turned back to the Magnetizer, said steadily.

"If you two know the secret of this city, know what everything is about, I command that you explain it to us!"

The robots advanced instantly at that, extended pincer hands and grasped her and Rod by the arms. They struggled a little for a moment, then as they realized no harm was intended they submitted quietly to being led out into the street. In breathless wonder the children came trailing on behind.

"Nice trick you've pulled!" Rod growled. "Lord knows what they'll do to us."

Eva smiled confidently. "They'll only do as they've been told. Machines can't reason. Unless I'm mistaken we're heading back to the laboratory. . . ."

She was right. Without pause the robots marched them into the place, released them and walked over to one of the massive machines. It was unlocked now; everything was unlocked. The whole Pandora's Box had opened.

With quick movements the robots switched the machine on, stood aside, and became motionless....

CHAPTER V
A Voice from the Past

ROD AND EVA waited, hardly knowing what to expect. Then they started forward a little as a concealed loud speaker inside the machine started to hum powerfully. Followed a clicking, probably a recording tape sliding in-to place. A deep voice started to speak slowly, in the Martian language. The two waited, tensely listening, stumbling here and there over a word. To the rear the children leaned forward in sheer awe.

"By all the chances of Nature and cosmos," the voice said, "it will probably be you seven children, grown to adult life, who will hear this, my voice, for the first time. Listen with great care! You own a city, the heritage of your creators. You are not natural children; you have no parents. You are synthetic, born of a test tube. When a race is all but dead and must have successors, synthesis is the only course. As I record these words you are still embryoes in the test tubes—but you will break free of your glass prisons, will develop, will live....

"Your brains, designed to retain magnetically produced impressions prenatally created, will be your guardians. By common impulse you will break free of your glass prisons, will live for many months on the carbohydrate deposits left around you in the laboratory.

"When that is consumed your minds will naturally lead you to fruits and their juices. You will live on them, grow strong on their nutriment, will fashion clothes from the leaves of the trees that bear the fruit. Why will you do this? Because it is impressed on your brains as a given factor that you must do so. It is a command, an inescapable urge. Because of the bodily construction we have designed for you, you will never touch water. It is rank poison. . . . Forgive me if I talk to you as yet unborn. I can hardly visualize you as adults, listening to me now.

"You are synthetic successors. Deep too in your brains is imbedded a certain combination code; each one of you, from the moment you grow old enough -to use your hands, will have this knowledge perfectly clear—the knowledge of the seven combination locks which seal the city.

"When you reach a period when puzzlement causes you to investigate, you will inevitably turn this knowledge to account, will unfasten the city in which you live. And because each of you have this separate knowledge it will save you warring and fighting among yourselves. Without all seven of you, the city can never be unlocked; instinctively, intuitively, you all know that. But now, because you hear my words, you have reached maturity, and unlocked the city. My voice speaks to you though my body has long since become dust.

"The city is yours. Build out of it a new heritage. It has everything you can require. Supreme genius built it for you. Train your thought waves on the central telepathic brain pan and robots of varying grades, their reception units geared to different telepathic orders, will obey implicitly.

"Both your sexes have male and female organs; you are not neuter. Marry; beget children—or if you desire, create them synthetically. The two servant robots will show you the formulae for life creation if you wish it. It cannot be done mechanically. It demands your own hands and skill. Attempt it only after long study. Your children, like you, will be non-water drinkers. That is, water will only be taken after natural filterization by plant life.

"We know now that heavy water is the cause of our downfall; your brains will know it, too. For generations vast internal lakes will remain. You will build new canal tracts from the Poles, allow the forests to break the water down to normal. If you choose you can even make the water normal by scientific methods, though it is probable that with your coming the age of water drinkers has passed away. Had we realized in time that we were dying and not gaining eternal life and genius, we would have forced the water to normalcy. The knowledge came too late.

"You need not ever fear invasion. The city is prepared with armaments against any possible interplanetary attack; though we do not for a moment believe you will have that to contend with. Only perhaps the third world will cause you trouble in the future. Be ready for it.

"I, the last of the race, salute the first of the new race... Salutations!"

The mechanism clicked and became silent. Rod arose from his deep thought and looked at Eva inquiringly, then at the silent children.

"Looks like we stepped in and anticipated things," he said at length. "These kids would have done what we've done in a few more years."

"Does that matter?" the girl shrugged. "We're not going to deprive them of anything—but we're certainly going to make use of what we've found. You realize of course that with all this at our command we can do anything? Even return to Earth?"

"And death?" Rod asked slowly. "Oh, no; there are better ways than that. Matter of fact, I'm thinking about Calva Neil and his short wave radio. He's definitely on our side, of course. If we could only get into touch with him..."

"It's an idea!" Eva whispered, her eyes bright. "Ten to one he'll still be experimenting with that short wave radio beam system of his. If we could catch contact with it sometime and let him know we're still alive...!"

Rod clenched his fists. "Then we could get Holroyd just where we want him," he breathed. "Right here under our fingers is a science mightier than anything he can devise. If we work carefully we can save the innocent and punish the guilty."

He fell to silence, pondering, thinking of the mighty radio rooms, listening to the dull throb of power from the city's vast engine rooms. Power—power—With which Baxter Holroyd, Dictator of Earth, had yet to reckon.

CHAPTER VI
Preparations for War

WITH the awareness of the supreme power they possessed, Rod and Eva spent a few further days taking stock of things under their command, particularly resources of attack. They studied too the central telepathic Magnetizer, discovered it was so sensitive that it reacted to thoughts from any quarter of the city, brought the required robots to do any possible service.

In consequence the two Earthlings found themselves installed in the living quarters of one of the great buildings, fan cooled to mitigate the heat of the energy-suns. Fruit food, made into all manner of delectable compounds by unfathomable machinery, was supplied to them at their slightest wish.

They had supreme comfort, reflected on the wiseness of the Martian scientist that had led him to lock up all this comfort until his synthetic followers were old enough to understand and not abuse its benefits. As it was now the children did not half understand it all, but for company's sake stayed near the two Earthlings, save when curiosity and remembrance of the recorded speech took them back to the laboratory to study curiously the dusty skeleton that represented the last man of their race. Where the others had gone remained a mystery, unless, as Rod believed, the last scientist had rayed them out of existence to stop any spread of disease from decomposition.

Had they wished, Rod and Eva could have lived divinely in this flawless Utopia, as first lord and lady of a new era, only that their Earthborn heritage allowed them no ease. Persistently, the memory of enslaved Earthlings returned to them. They evolved plans, ordered the servants to direct them to the radio rooms, and once again studied the wilderness of radio machinery, so complicated that it took them weeks of reference to charts and plans before they began to understand what it really signified.

As they had at first suspected the vast instruments were not only radio devices, able to span to the outermost planet if necessary—but also televisionary and telescopic, working on some system of light-wave convergence that was beyond the understanding of anybody save a genius. Not that either of them bothered about the inner workings; they were faced with quite enough difficulty understanding the controls.

But results they got—by degrees. They trained the mirrored picture of Earth in one of the huge telescopic screens, brought it close enough to study its blurless, city-strewn image, the seas thick with maritime commerce, the air filled with speeding shapes. Progress, yes; all of it operating as usual for the good of one man—Baxter Holroyd.

Rod's gray eyes glittered as he surveyed the world. He glanced up at the girl and found her face expressing similar thoughts to his own.

"Revenge, eh?" he murmured, and she nodded stonily.

"Call it justice, Rod. It's more accurate."

He turned aside and studied the chart he had made of the Earth space ship's automatic control device. It gave him the precise wavelength on which to work, identical with the one Calva Neil had used to guide the vessel to Mars... Satisfied, Rod settled firmly in the chair before the banked switchboard and altered the frequency controls, hurled forth a radio carrier beam across the 40,000,000 mile gulf.

Another screen, immovably connected with the carrier wave, came into action and revealed the light-fast journey across infinity. Earth hurtled upwards out of the abysmal gulf: the carrier wave went clean through it, out beyond into space... Slowly Rod adjusted the controls, brought the carrier beam under control.

His fingers toyed over the switches he had learned to use. Silently he marveled at the static-free power of the apparatus. He spoke mechanically into the transmitting microphone.

"Calling Calva Neil... Calling Calva Neil..."

He kept up the call incessently, the girl taking it over when he got tired. But between them it took two weeks before they got any response. Then it was in Calva Neil's own voice, obviously much puzzled.

"Calva Neil replying. Who's working on this wave system? Is it a cut-in, or what?"

Rod grinned with delight and stared at the screen. The carrier wave had picked up the inflowing light waves from the source of origin, revealed the blond-headed, ruddy checked young scientist seated in his laboratory, his baffled blue eyes searching his apparatus. Around and behind him loomed the essentials of his brilliant system. A brief shifting of the carrier wave brought in the entire laboratory; save for Neil it was empty. Therefore safe to speak.

"This," said Rod slowly, swinging back to the scientist, "is Rodney Calab calling you—from Mars!"

Neil's amazement was so profound Eva burst into a laugh.

"It's—it's impossible!" he gasped. "And yet I... I was testing this carrier wave in readiness for ships to depart from Earth into the void. Ships bound for Venus as soon as they're ready. Somehow you must have gotten onto it as it experimentally reached to Mars..." He paused, rubbed his high forehead. "Guess I'm going nutty," he said curtly. "Whoever you are you're pulling a damned silly joke, cutting in on my length."

"If I told you you were rubbing your forehead with perplexity what would you say, Calva?" Rod asked calmly, studying the screen.

"Huh?" Neil stared wonderingly in front of him. "You don't mean you can even use spatial television?"

"I'm Rod, and this is Mars, and I'm using television," Rod said briefly. "Get that straight, Calva. There isn't any time to waste. You're alone, aren't you?"

"Sure. I'm working for Holroyd on this short wave for a space expedition and—But you know that. He may send for me at any moment. Say, I'm darned glad you're alive. How the devil have you managed to—"

"Keep quiet and listen!" Rod interrupted, then he went into a careful description of all that had taken place. The distant Neil sat in astounded silence as he listened.

"So now you know," Rod finished grimly. "Holroyd's reign is coming to an end. I want you to take action, take up the plans where I was forced to leave off. You've got to start an uprising, a revolution—anything. Get together all the people who are opposed to Holroyd's rule and collect them so far as possible on the western side of the country. That'll fix Holroyd in the eastern half, and his men will concentrate there too.

"Definitely you'll start a war, but carry on with the assurance that I'll send forces to aid you. I want Holroyd's army drawn into the open so I can eliminate it—and the more you can gather in the west the better. I'll give orders for the west to be left untouched. That clear?"

"Clear enough," Neil nodded; "and I think I can manage it too. The cities to the west aren't as closely guarded by Holroyd's minions as eastern New York. Point is, are you sure of your forces? Remember that Holroyd has heat rays, bacteria bombs, gases, ultra fast rocket ships—-"

Rod grinned mirthlessly. "Leave that to me. I've got stuff right here that'll turn Holroyd inside out. You just do as I say. When you're free to communicate again do so. You needn't give me any signal when to start; this telescopic appartus gives me a very good view of all that's going on. Good hunting, old man!"

"O.K." Neil's face was set and purposeful. The vision of him faded as Rod broke the carrier wave transmission.

With hardly any intermission, sleeping in turns, Rod and Eva kept a constant watch on the telescopic screen, held Earth steadily in the field of vision in its journey through space—but again several weeks elasped before they saw any sign of a change, and then it was sudden and violent.

Explosions vomited from various points of the United States, centered particularly in New York. There was evidence too of convergence of battleships towards the eastern shores. They were thick in the Atlantic. The air too was filled with hurtling, darting shapes.

"War!" observed Rod, lips tightening. "Neil's taken the plunge all right. Dictator armies versus the oppressed, with Holroyd at the head of the former. See those black bombing planes? They're his. The white ones are Neil's own—the ones we were going to use when we were captured. Now we can distinguish between them we can get busy."

He issued a sharp command. "Army, prepare for action!"

It was no meaningless injunction he uttered. Through the intervening time he had learned enough of the vast Martian robot army to realize their artificial brain pick ups were geared to all militant orders. Naturally, they could not reason, but they could follow out a whole chain of orders given the initial stimulus. With their actions watched in a televisor screen they could be controlled to do anything, supreme in the fact that they were deathless, unerring.

Turning a little, Rod switched on the short-length televisor wave, directed it to penetrate to the robot hall two blocks away. Activity was everywhere in the great space. The robots, the command received, were marching. In ten minutes, under further orders, they arrived in the space ship hangar, paused in orderly groups before the fifty vessels. As Rod had reason to know, they were already equipped with all manner of war devices; the armament room's supplies would not need to be touched.

"Enter forty nine ships! " he ordered; then glanced up at the girl. "The fiftieth one is for us," he explained—and watched the airlocks shut like a row of eyelids.

"Fire your fuel chambers!"

The fuel, which was apparently a rich magnetic oxide, fired not by flame but by a complicated pressure process, hurling terrific recoil power into the gleaming tubes. At Rod's order all tubes flared redly, filled the gigantic place with poisonous blue vapors. Again he snapped an order. The roof slid away under a robot's tug at a lever.

Gently, ordering and countermanding, maneuvering literally with his thoughts, Rod forced the robots to raise their machines in a glittering armada upwards through the roofless opening, then onwards toward the mighty shaft which gave egress to the surface.

The machines traveled swiftly, held perfectly in the televisor screen. Television followed them as they swept up the long shaft, outwards over the desert, up into the star ridden void towards the green star of Earth.

Rod sighed with relief. The most difficult work was over. Forty nine avengers were on their way.

CHAPTER VII
Holroyd's Defeat

ONCE the machines were steadily on their way, requiring but little actual guiding in empty space, Rod turned his mind to other things and left Eva in charge.

The weapons owned individually by each ship were not mere ordinary implements of war, but devices infinite and terrific in potency. For one thing, each vessel was supplied with a power pick up, by which it received power from Mars itself, sent over another radio beam—power born of Mars' magnetic currents, concentrated at the North Pole with terrific intensity from the nickel iron under terrific pressure deep in Mars' core. Power begotten of the planet's dynamo like qualities against the ether.

This power, which gave the city its strength and resources, also possessed an inconceivably strong surplus, which, passed through magnets, transformers and induction coils could be given to the armada over radio beam and thus utilized. Rod had only the vaguest idea what this power might do. That it fed the vessels' armaments he already knew, but to what extent in action he could only picture.

Satisfied that the power transmitting apparatus was in order, ready to be released by a robot the moment he gave the command, he returned to the radio room and took over the girl's work.

There was one advantage with the Martian vessels—the terrific speed they could attain and the impossibility of the occupants collapsing under the accelerative strain. So it was that the ships streaked across infinity at a speed nearly equaling that of light itself. The passage of forty five minutes revealed via the televisor that the Earth filled the whole field of view in front of them.

The telescope, on the other hand, revealed a flurry of excited action passing over Holroyd's army, concentrated in and around New York, then stretching half across the less congested regions of the United States to the opposing army of Calva Neil in the west. It was not a flurry that betokened a weakening of morale, but a sudden gathering together of massed forces.

The invaders had evidently been sighted. To question the why or wherefore of their coming was not possible in the urgency. But Holroyd must have wondered at the defiance of his orders when he called on Neil to stop the personal war and instead unite in common attack against the unknown enemy. Neil, knowing full well what he was about, bluntly refused, continued to harrass the Dictator's army, his white planes zooming and power diving relentlessly.

But on the ground he withdrew his warfare further westwards out of range of the battle he knew was to come.

Curtly Rod gave the. order for power release, issued orders to his now forty million mile distant army.

"Remember to attack only the eastern coast and the black airplanes-no other..."

He waited a few moments. Martian ships and the darting, inquisitive invaders of Holroyd swarmed through the sky. From down below anti-aircraft devices stabbed upward with livid beams of violet. One Martian ship, caught amidships, crumpled instantly.

Rod set his teeth; the power would be there by now, ready for the fleet to utilize.

"Fire!" he commanded, and watched breathlessly with Eva clutching his arm.

The forty eight machines abruptly glowed deep violet. Energy, released by their power pick ups, encompassed them in a veritable shell, energy which forced the molecules of the ships' construction into such a tight interlacing, invisible shield that a heat ray was instantly deflected like water against steel.

In that instant Holroyd's fleet realized it was fighting something beyond its powers. The shattering strength of their flame guns, their mightiest shells, made not the least impression.

The Martian machines, incredibly fast, hurtled in and out of the slower Earth masses, flung forth ethereal waves that had the effect of destroying molecular cohesion and forced the vessels to -literally fall to bits in mid air, dropping twisting, turning ?gures to the raging battle ground below.

Dark red rays, drawing their power from the inexhaustible source on distant Mars, belched abruptly through the Martian vessels' screens, stabbed to Earth. An entire army unit, struggling manfully with anti-aircraft devices in the center of New York, vomited skywards in a sheet of flame in which all trace of matter had utterly gone. Instant conversion into energy was the only explanation, produced by still another ether vibration forcing electron and proton into contact and thereby canceling out atoms into splashes of cosmic rays.

"The tallest building below you—destroy it!" Rod commanded.

He knew that building; his face was rigid with bitter hate as he regarded it. Holroyd's Executive Building, having within it the Hall of Judicature. Also it was the spot from which he would certainly be directing operations.

Rod waited while his message ?ashed across space, then as it was received the impregnable Martian fleet swept round to obey. Here and there, essaying a last desperate attempt, the Holroyd machines hurtled up in a solid wall for a final stand. It was final indeed.

A blasting wave of destruction withered against them, sent them hurtling in all directions, smashed them, melted them, blew them into infinite nothingness. Untouched, glowing steadily, the Martian armada sliced through the barrier, swept down in an avenging horde on the tall tower of Holroyd's headquarters.

The tower vanished in a brilliant ?ash of light as nameless power snicked at it. Then, maneuvering round, twenty of the vessels trained the full' force of their devastating powers on the edifice. Bricks, metal, all possible formation, lifted heavenwards out a mile deep crater! Dismembered bodies, debris and smoke spouted to the sky. The scurrying people around the building flew backwards under the terrific discharge of superheated gas and compressing atmosphere.

"Continue!" Rod ordered implacably; then turned a little as Eva grasped his arm.

"Rod, isn't it enough?" she asked in a low voice. "After all, you have the mastery now and-"

"There are minions of Holroyd in that army," he retorted. "I'm going right through to the finish! "

He watched in brooding contentment as the armada returned to the attack—but the result now was a foregone conclusion. No ship, no human, could stand against fleshless robots, planetary power, and incredibly destructive devices. On the eastern side of America mile upon mile of battling men were incinerated or buried. Ships ripped to pieces, sank in boiling tumults.

In the air, black ships split in twain or fell, rays swaying crazily as they fell on the maddened hordes beneath. Blackness ate into the ground as it was literally burned into ashes under the feet of the demoralized thousands.

But, still true to orders, the Martians made no effort to attack the western side of the States, whither the survivors of Holroyd's army were painfully struggling, all desire for fight gone.

"It's massacre!" Eva said suddenly, as the last two black airplanes went down to the ruins below.

"Justice," Rod answered quietly—then he turned sharply as the remote control radio set suddenly livened on its signal tube. Instantly he closed contact.

"Yes?" And he had to wait for the light-fast radio wave to hurtle to Earth and return with the answer. On the screen appeared Neil's grimly triumphant face.

"Call an armistice!" he cried. "We've definitely won. What is left of Holroyd's army is on the run. We're ready for them if they ever get this far, which I doubt. Oh, boy, I don't know what you've got packed into those ships, but it sure is hell!"

Rod smiled faintly. "O.K., I'll have the ships descend and there wait for further orders. I'm coming back to Earth with Eva at the earliest moment—"

"You realize, of course, what you've achieved?" Neil asked, his eyes shining.

"I guess so," Rod assented. "We'll bring living back to what it should be, where every man can have liberty. I've decided to lock up this city when I cleave it. We've had our worth out of it, and it's not our job to interfere with the natural legacy of these Martian children. None the less I think they'll be useful friends to have. Their city here has such science that it'll be wise for us to cultivate it. And I mean cultivate it," he finished grimly. "Not use it for destructive purposes."

"Naturally, you'll be the new leader of Earth," Neil said quietly.

"I hope so... Well, Cal, that's all for now. You've done a swell job. See you on Earth."

Rod switched off, turned to the girl, glanced across to where the children were watching with their usual silence. Then he said quietly, "You think it's our duty to lock this city when we leave?"

"Definitely," Eva nodded.

Rod turned aside, pondered for a moment. "Guess the robots and ships don't belong to us," he commented. "They'd better come back here." He broke off, said sharply, "Cease fire! Return immediately! "

"When they're back we can leave," he smiled. "And shall I be glad. I'm itching to get back to Earth for one very good reason—"

"And that is?"

"So I can have a darned big glass of water!"

Behind them came the sound of childish giggling as their lips met and clung.