THE BRAVELY questing light of Hartwick's helmet beam disclosed the tunnel abruptly becoming five more as it dipped sharply down. He halted, perplexedly scratching his transparent visor with a metal-gloved hand.

Unable to stop short, Boule, the expedition's photographer, tripped into him, cursed, and cursed again as the three scientists piled up against his back with weirdly echoing crashes of spacesuit against spacesuit.

"Careful, Hartwick, careful!" Lutzman's bass voice warned into their headsets from the rear. "Another tangle like that and we'll rip the line to Bhishani."

The guide nodded abstractedly at the bioareologist. He spent a long, careful glance at the faintly fluorescing cable connecting the loops in their suits and stretching lengthily behind them through corridor after intersecting corridor to the assistant archaeologist on the surface. The cable was their link with life.

"Five more branchings," he stated at last, pointing ahead.

"An honest-to-Minotaur labyrinth," Punnello, the senior archaeologist, muttered as he extricated himself from between Boule and Lutzman and peered over Hartwick's shoulder. "We differ from Theseus only in that we use an insulated wire instead of a spool of thread."

"And that we won't find a Martian version of the hull-man monster in the heart of this neurotic temple," the bioareologist pointed out. "Not that I look forward to it; he'd be rather hungry after—how long?"

Punnello shrugged his shoulders resoundingly. "At least a quarter of a million years since Priipiirii had a worshipper. No, from those wall friezes we've been passing, I'd say he was arthropomorphic enough—as crustacean as the race which conceived him."

"Which isn't very crustacean according to Earth standards," Lutzman observed. "Why does he continually change his sex? When we dug away the sand and stepped through that first trapdoor on the roof, there was a large statue of him as a male in front of the cross-passage. After the first level, there were only female representations; they became hermaphrodite and later neuter. Down here, he shifts back and forth through all four in each frieze. And yet the Priipiirii ideogram on each of his pictures is unmistakable.

"Why, for the matter, isn't there an occasional hint of the daily life of the average mortal, such as we found in the other temples? They showed their gods being worshipped and occasionally disregarded; here, there is a steady reiteration of Priipiizii only—Priipiirii at work and at play, as it were. Odd, that business of play, considering how evil other Martians thought him."

"Don't you?" Boule asked suddenly. "I've been snapping flash shots of this jovial character in all his phases and I like him less all the time. I don': know why ancient Mars tabooed him, but he sure radiates the impression of happy executioner. Frankly, I'm sorry I came on this jaunt. I don't relish wandering around in the place where the Martian devil was worshipped; and I still haven't accepted those trapdoors on the roof of the temple-as if the inhabitants knew it would be buried by the desert one day."

Hartwick paused in the middle of an impatient gesture at the five tunnels ahead of them and swept his helmet light through the gloom until it came to rest on Boule's visored face. Back in Bubbleburg, when he'd been commissioned to lead an expedition to the fabled temple of Priipiirii, the Martian Archaeological Foundation had assured him that the scientists of the party would all be picked, psycho-certified men.

But they'd said nothing about guaranteeing the photographer's stability, the desert guide remembered uncomfortably. Boule was one of the few lens-hounds in the archaeological paradise that the dead planet had become: he'd taken pictures of the early excavations at Gulthum and Yeyarneh when the first mumbling hints of the Priipiirii cult had been noticed; he was a logical choice.

"Very possibly they suspected the end of their canal civilization would invite the desert to creep forward again," Punnello suggested. "I'll admit it is rare to the point of nonexistence for a race to build with a view to its own extinction, but remember what a highly intellectualized—rather than mechanicalized—culture the Martians enjoyed. They were definitely telepathic, probably prescient too. And the reason why Priipiirii frightens you so, seems so alive—"

"If you don't also feel he's alive, why use the present tense?"

"Hah?" The archaeologist's jaw sagged against his facepiece.

"All right!" Hartwick's voice interrupted brusquely. "The big question right now has nothing to do with whether this purple crayfish has horns or a forked tail. Down which of these five holes do you professors want to be led? The slope is getting sharper all the time, so we have to be twice as careful as a trip to Mercury. And if we meet any reincarnations, Boule, don't forget that you, Lutzman and Punnello, each have deadly little kazoos in your mitts, and I'm carrying a bazooka."

"I only wish you weren't holding any sort of rocket weapon, Boule," he added to himself. "Talk like that in a place like this!"

The archaeologist turned to Lutzman. "Considering the one-sided sensory orientation of the architects; I think we might as well continue bearing hard to the left. Seems correct, up to now."

"Left?" Lutzman turned from a frowning examination of a mural depicting Priipiirii swimming twistedly in a canal—the back of his thorax and the front of his abdomen submerged. "Not necessarily if—"

THEY all spun round as the hideous clatter began in their rear. The bioareologist stepped forward and squinted up the incline that slanted past multitudinous passageways to the desert surface.

"It's Bhishani!" he shouted. "Must have fallen through the trapdoor and couldn't get to his feet in time!"

Hartwick wasted a quick glance for the sake of certainty at the limb-threshing figure rolling toward them like a compact avalanche. "Get over to the wall!" he yelled. "If he hits us—"

He ran to his right, dragging Boule with him, while Lutzman and Punnello scrambled to the opposite side. Before either pair could correct their error, the Hindu archaeologist bounded into the taut cable connecting them across the tunnel and snapped them around him in a churning conglomeration of bodies.

They bounced hurtfully through the center corridor, ricocheted against a slanting wall and crashed agonizingly to rest upon four red idols on the floor of a spherical room.

Hartwick was on his feet first, testing his suit for leaks and using muscle flexes to determine if any of his bones were broken. Finding nothing, he reached down and angrily turned Bhishani on his back. "Do you realize what you've done?"

The assistant archaeologist's face sickened to blue under its smashed visor. "Felt a tug on the line," he gasped thinly into his headset. "Lifted trapdoor—leaned over—slipped—not my fault—why did you tug on—" His throat rattled in the almost airless cold.

"Hey, Lutzman!" the guide snapped at the Martian biologist who was groaning himself into an upright position. "Fast! Help me work his head-screen over the crack in the visor."

Together, they tugged at the round piece of metal at the top of the helmet. The headscreen, too, had been bent by the fall. It was stuck tight. Hartwick abruptly stopped working on its broken hinges and tore it out of place. He fitted it rapidly around the visor and snapped the emergency clips into position. But by the time he saw the rip in Bhishani's oxygen tank, the man's body had relaxed out of life.

"Poor guy," Boule muttered. "Gone just like that."

Punnello was also on his feet. "Perhaps—some of our oxygen—"

"Not a chance," the guide told him. "Mars is too fast for you."

"I can't understand how he felt a tug on the line. If any of us pulled at it, the others would have noticed."

"Work it out tomorrow," Hartwick invited. "Meanwhile, the only way we can be sure of getting out of this lunatic maze is by following the cable while it still reaches to the surface. Let's go!"

He started for the tunnel opening where the wire lay slack, his companions following.

The line was piled inside the tunnel mouth, coil upon scrambled coil!

"Bhishani must have torn it loose when he fell in," Lutzman almost squeaked. He regained control of his voice. "And the desert wind blew it down."

Hartwick nodded and kept going. "It's still roaring. You can feel the rattle of sand on your visor. We can find the trapdoor that way."

He stopped a moment later as the wind disappeared. "Trapdoor must have been blown shut. But the sand makes a track."

The winding path of sand drifted down casually, lazily—but completely. It went past them into the room of four idols and collected in little piles upon the harsh stone floor. Ahead of them, they could see that the tunnels were perfectly clean under the glare of their helmet beams.

"You can't call this an accident," Boule began in a high voice.

"Shut up! I think I can remember the turns we took. We simply reverse them going 'back. Let's keep moving before it gets hazy."

WITH Hartwick leading, they raced up the weirdly offshooting corridors in their ungainly spacesuits. Their helmet lights made the rapidly successive friezes of the temple's god seem like a jerky motion picture. Suddenly, the guide slowed to a walk.

"What's the matter?" Punnello gasped from the rear.

"No slope. It's gone level, and we should still be climbing."

They came round a curve in the tunnel—and into the spherical room Bhishani's body lay near one of the idols. Piles of sand....

One by one, they filed in. Boule said huskily, "A circle."

Hartwick rang a fist against his open metal palm. "Look," he said at last. "Maybe I'm hearing the flutter of bat wings in my bell tower, but I have the odd idea that the maze was rearranged."

"Obviously," Punnello nodded. "The gradient which was present everywhere when we came down has disappeared. But I suggest—and for other reasons than because that way madness lies—that we temporarily gloss over that explanation of our failure to escape—er, to reach the trapdoor. I suggest we concentrate on things like routes."

"It does seem—" the bioareologist cleared his throat. "No."

Boule walked over to the four idols and examined the table at which they sat. "Saea! They're playing a game of saea. Saea!"

Hartwick, having observed him remove his kazoo from its holster, unslung his bazooka cautiously. "Know anything about saea, docs?" he asked, his eyes on the photographer. "Does it help?"

"Not very much," Punnello said slowly as he too looked down at the odd altar. "Directions for play have been deciphered in every Martian ruin, but it's a little too rich for our cerebral blood. The rules are a cross between chess and the Japanese game of Go, with the addition of crevices where pieces can be held out of play for a varying number of moves. Why a sculptured problem in saea, now?"

Lutzman moved up. "And do you notice who the players are? Our old friend Priipiirii—all four of him!" He swept an arm around at each enormous scarlet idol. "Masculine, feminine, hermaphrodite, neuter."

"Red's the Martian color of death, isn't it?" the guide inquired.

Punnello nodded abstractedly. "And life. In fact, the combination of the two expresses it better. Here, perhaps— Suppose we work on less metaphysical subjects. Much safer, at the moment."

They agreed rather hastily. Hart-wick drew a stylus and a sheet of recordio film from his flank canister; the four of them squatted on the floor near the body of the assistant archaeologist and discussed the matter of routes. They argued about each turn they had taken until they were all convinced of each one. The guide copied the list backwards, in the order which they would come across the intersections while returning. Then, they left the room again, carefully reversing each change of direction.

Fifteen minutes later they were back. They discussed the list, made a few alterations and once more left through the tunnel in which the cable was piled.

The sixth time they came back, Hartwick scaled the sheet of recordio out into one of the tunnels. It spun away, drifted easily back and floated to the floor.

"One last idea," he said. "This has to work."

"What's the use?" Boule demanded. "Let's admit what we're all thinking and really get someplace."

Hartwick tightened his grip on the bazooka. "I don't know," he said with a grim attempt at humor. "Are we all thinking?"

The archaeologist shrugged. "We start with the premise that we are the first humans in this temple, and that no humans on Mars have any desire to do us harm."

"Check," the guide told him softly. "Just carry that ball, doc."

"We accept, though on less evidence, that there are no extrasolar creatures operating here, since there was no indication of this site being disturbed and no one has previously observed such creatures in the system. Furthermore, there is no race in the system, other than humanity, which possesses intelligence. Finally, for almost a hundred thousand years, the only animal life which has existed on Mars is the extremely primitive polar beetle. Therefore, the tugging at the line, the death of Bhishani, the loss of the wire path to the surface, all of our difficulties—including the apparent rearrangement of the labyrinth may be laid to mechanical contrivances which the temple's builders left behind them out of viciousness or religion.

"Such contrivances are not rare in Terrestrial temples, especially of this type. However, we have the fact that Martians tended more to things intellectual—the esthetic and philosophical, say—than to material enterprise. All that we have seen on Mars supports this view: it would seem to be accentuated among this particular people, where, with the exception of the trapdoors, not one remotely mechanical device has been observed. And if you add the almost sentient malevolence with which we have been frustrated, logic leaves only—"

"Only what?"

"Priipiirii," Lutzman finished very gently for the archaeologist, "Priipiirii, and evil deity."

"Well, I'll be— I've been sitting on that notion like crazy, but I never thought a bunch of scientists could swallow it!"

"Reject the implausible," Punnello intoned as if the words were a hymn, "and what is left is the plausible."

"It's true, isn't it?" the photographer demanded. "You feel he's alive, he's near us, don't you?"

HARTWICK looked from one helmeted face to the other, his beam stabbing three separate times around their heads to the curved walls. Then he sat down.

"All right. I'll admit I believe it. But why should I?"

"Well," the archaeologist sank his head on his chest and minced a tiny, meditative circle. "It has been suggested that the powers ascribed to some of the Terrestrial deities really existed, at one time or another, in some form or another; that the very act of widespread belief in a particular god called forth something like that god with some of his powers on a temporary basis. Now, generally, this theory may well be grit for the herds; but here, where you have a race intellectualized out of all human conception, that had achieved a philosophical level higher than the scientific one we may reach in a thousand years, a race that had telepathy, possibly prescience of a sort, and various mental facets outside the scope of our imagination—such a race might well create a living god from its collective mind. A sort of racial super-id."

"But why would they need a god? with all that mental equipment, I just can't see them praying exactly."

"Prayer and sacrifice and the granting of favors thereby, is only one of the uses of a divinity. He can fill certain psychological needs which the race may even recognize as such. For example, the warlike inhabitants of Asgard rarely gave boons to suffering Norsemen; they carried on a constant heaven-shattering warfare, however, in the last great battle of which humanity was merely an inconsequential ally. They typified the precarious, bloody existence of the race which had conceived them: they were satisfactory."

"I see that. But how did we get Priipiirii into the psychic flesh again?"

"By thinking about him, by believing in him. Those wall friezes were probably not designed for that purpose, but seeing them helped solidify our mental pictures of the god. I think Boule was the first affected. since it was his job to take photos of the most significant sculptures. All of us were slightly, as these people knew how to pack an esthetic wallop-but Boule most of all. When he came to believe that Priipiirii was alive—well, Bhishani felt a tug on the line."

Hartwick exhaled against his visor. "Okay, I'11 ride along. But we have a little problem of diminishing oxygen. We do what?"

"Find out what he wants," Boule replied loudly. "And give it to him. Sacrifices, propitiation—"

The archaeologist shook his head. "Not sacrifices necessarily. Propitiation if we can deduce enough of his innate qualities to make it possible. But that will be very difficult, considering the alien quality of his former worshippers, the very little data and time we have available for deductions—Hello! Speak of the devil and you do get data!"

Above their heads, in the exact center of the room, a violet cloud hid appeared. Luxuriously, it formed itself into the familiar figure of Priipiirii—masculine version.

Invisible fear dripped through their airtight suits and drenched their skins.

LUTZMAN rose, his eyes narrowed. "Why do you suppose he shows himself? Because we all admit belief in him now? Because he wants to gloat over our helplessness? Because he's vain? He doesn't seem interested in making any overt move-all he can do, hanging up there like that, is confuse the issue."

"He wants worshippers, he wants sacrifices," Boule insisted. "All of the dying-god cults on Earth follow that pattern. It must be the same on Mars. Changing from sex to sex—I read somewhere that was a manifestation of what they call a dying-god. Right, Punnello?"

"No. Occasionally there is a hint of hermaphroditism or feminization in some of the dying-gods Earth has known in the past. But not all four forms at once. Not even on Mars—"

"What's to prevent us from no longer believing in him?" Hartwick wanted to know. "Then he and his powers no longer exist."

"With all these statues and pictures around you? Hah! That's like that game—'don't think of a white horse!' No, we have to work out the component parts of his nature. This race engaged in both sex and agriculture in a very offhand—or offclaw way— so he couldn't be a regenerative deity. Now, can anyone say what's really intellectual?"

No answer. They stared up at the carelessly undulating horror.

"I want to examine his solidity," Lutzman observed suddenly and slipped his kazoo from its holster. Boule and Hartwick both leaped at him—a moment tardily.

The tiny rocket shell whizzed through the hovering monster and exploded against the domed ceiling. A crack appeared in the highly polished stone, was wiped abruptly clean again as Priipiirii shot over toward it. He raced around the inner room as if inspecting it for further damage. Finding none, he resumed his position.

Hartwick had reached Lutzman first and plucked his weapon away with a muscled grab. Out of the corner of his eye, he saw Boule jerk to a stop and level his kazoo at the specialist in Martian biology.

He swung back again fast, desperately. Boule pressed the firing stud and threw himself aside. The rocket hissed past Hartwick; an immense gong seemed to ring in their headphones as Lutzman exploded before he could scream.

The guide tattered past Boule, sickeningly off balance. He knew the gun was centered on his back, that momentum was carrying him too fast in the heavy suit to permit him to turn and fire first. And there were three more rockets in the kazoo's chamber....

He cursed all unstable photographers and the dimwitted archaeological foundations that permitted them to go on such highly charged expeditions without adequate psychological probing. He heard the sibilant exhalation of a shell and his body tried to hold itself together against the moment when it would be ripped apart.

Then there was the explosion-and he was still alive.

Hartwick turned slowly. There were clean bits of metal and ugly shreds of flesh all over the room. Outside of the twisting, somehow exultant Priipiirii, he and Punnello were alone.

The archaeologist sheathed the kazoo with which he had killed Boule before he could fire at Hartwick. "Sacrifice," he mumbled distractedly. "He was trying to sacrifice you as well as Lutzman for having blasphemed. The fool! I tried to tell him Terrestrial standards of divinity didn't apply. He was so desperate of his own life, so anxious to placate-Imagine trying to propitiate a god with the subtle origins of Priipiirii by a hideously blunt sacrifice!"

"Blunt or no, that little rumpus sure cut down our strength. By any other name, they're still sacrifices—and from the look of that crayfish, I'd say he was enjoying them. Thanks for the shot, doc."

Punnello nodded and grimaced at the crustacean god who was now writhing in unmistakable ecstasy. "Evil, evil. Yet it's obvious there's no direct malice involved. With his powers—consider the ease with which he patched the hole in the ceiling—' he could undoubtedly dispose of us in unnumbered horrific ways. Somehow or other, we are giving him the kind of worship he wants—how? The god of the most advanced and most decadent of the mind-stretching Martians—from what we've deciphered in the other tombs we know that his people were both detested and immensely respected. But what is he?"

Hartwick frowned. "Look, I've been wondering. All those pictures of him we saw as we came down, the ones you said made us believe in him. Couldn't they have been put there just for that purpose?"

"No. Much more likely, they were meant to help the creatures who worshipped him, by giving them clues as to what to expect. It just occurred to me: this god or super-Martian, who was created out of the united aspirations and interests of a race, probably destroyed it. There is every indication that he is highly egocentric; the other temples hinted at his destructiveness. They didn't discuss him, however; almost as if they were too close to worship themselves!"

The guide nodded and pulled a long stick of chalk from his flank canister. "Save it. I don't think you could work out his nature if you stood on your head and walked around on your ears. Who knows what in space those brainy crayfish considered holy? And if we did figure it out, how much chance would we have of giving him what he wants? No, let it ride. I said I had one last idea as to how to crack this joint—let's try it."

Gently, Punnello smiled at the chalk. "Oh, that. No, I'm afraid it won't work. If he can rearrange the maze, if he can repair holes we make in the stone with our rocket shells—"

He walked slowly to the four idols sitting about their involved game. "Somehow, I'm positive that this is the answer. Why all four manifestations of Priipiirii playing saea against each other? Why an altar which is nothing more than a problem in saea? If we can solve the problem, now, it might loosen something essential in the god's powers. There had to be a reason for this stone game."

"Listen, doc," Hartwick urged. "I've seen too many archaeologists talking through the top of their heads because they tried to learn saea. And this problem they set up here is bound to be ultimate stuff. Give it the go-by, and come with me."

Punnello hadn't heard. He was standing before the board, studying the carved pieces carefully. From time to time, he made motions with a metal-covered hand.

HARTWICK shrugged and strode into the cable-littered tunnel. He bent over and made a cross on the floor every ten steps. "If my oxygen holds out, I should make it," he pondered. "No more circle-walking."

After he had gone a hundred feet, he gave up and wandered aimlessly: Chalk cross-marks had appeared on the floor ahead in every tunnel....

When he arrived in the spheroid room again, he walked directly to Punnello's gesticulating figure. He froze when he saw the archaeologist's contorted face, now screaming at the four red idols, now raised in anguish to the god floating in his carnate purple. He understood the muted gibberings he had been hearing in the headset for the past fifteen minutes—and had dismissed as Punnello's necessary self-communion over the saea problem.

Punnello stood before the immutable saea problem—and was mad.

The guide clenched his fist fiercely, then sighed and opened his fingers wearily. There was nothing to strike, nothing to grip, nothing....

He dropped to the floor and spread himself on his back. The moment he lay down, Priipiirii left the insane archaeologist to undulate over him.

"What are you?" he wondered, noticing the first faint foulness in his oxygen supply. "What do you want? Why do you tear us down this way, when we've done nothing to you? You aren't the kind of god who would punish for desecration of his temple?"

As if in reply, the deity went through all of his sexual forms, ending up as masculine once more. Hartwick watched. cursing.

His sanity began to slip into the narrow chasm of the problem. He got a grip on it by reverting to practical approaches. Lutzman had taken a shot at it. Perhaps—

His oxygen already was dangerously low.

He shot at it several times. Useless. Weapons were useless here. Lutzman shouldn't have tried. If Lutzman hadn't been killed he might have been able to work out the god's desires from crustacean psychology.

An angle! His mind, fogged by the poisons his respiratory system was inhaling in lieu of air, groped desperately. What—what would be a highly intellectuallized crustacean viewpoint? Not really crustacean, though—Martian biology was so different that bioareology was the name of the science here—Lutzman, now, Lutzman might have....

Desperate struggling through the night that was coming down overhis brain. It was such torment to breathe—to think—Crustacean—that was it-all he had to do was work out something peculiarly crustacean-

Priipiirii replied again. This time, he became a fish, a mammoth, a Martian polar beetle, in turn. Then himself again.

Hartwick's mind, Hartwick's life, slipped out too fast for him to hold on. Faster—

Above him, the god watched the approaching extinction of his last worshipper—which meant his own extinction, too—with courteous delight. Faster and more ecstatic grew his squirmings over the two dying lunatics in the temple of a dead and decadent race. So sweet to receive again obeisance from insanity!

For was not Priipiirii most gloriously and intricately the God of Puzzles?