And the blaster was coming loose. In fact, it came free so suddenly that Bigman's numbed fingers nearly dropped it.

"Sands of Mars!" he muttered, and held on.

If he had known where in the tentacles a vulnerable spot might be, if he could have blasted any part of those tentacles without killing either Urteil or himself, his problem would have been simple. As it was, there was only one gamble, not a good one either, open to him.

His thumb worked clumsily on the intensity control, pushing it down and down. He was getting drowsy, which was a bad sign. It had been minutes since he had heard any sign of life from Urteil.

He had intensity at minimum now. One more thing; he must reach the activator with his forefinger without dropping the blaster.

Space! He mustn't drop it.

The forefinger touched the proper spot and pushed against it.

The blaster grew warm. He could see that in the dull red glow of the grid across the muzzle. That was bad for the grid since a blaster was not designed to be used as a heat ray, but to deep Space with that.

With what strength was left him, Bigman tossed the blaster as far as he could.

It seemed to him then as though reality wavered for a moment, as though he were on the edge of unconsciousness.

Then he felt the first glow of warmth, a tiny leakage of heat entering his body from the laboring power-unit, and he shouted in weak joy. That heat was enough to show that power was no longer being drained directly into the voracious bodies of the heat-sucking tentacles. He moved his arms. He lifted a leg. They were free. The tentacles were gone.

His suit-light had brightened, and he could see clearly the spot where the blaster had been thrown. The spot, but not the blaster. Where the blaster should be was a sluggishly moving mass of gray, intertwining tentacles.

With shaky motions, Bigman snatched at Urteil's own blaster, setting it to minimum and tossing it past the position of the first. That would hold the creature if the energy of the first gave out.

Bigman said urgently, "Hey, Urteil. Can you hear me?"

There was no answer.

With what strength he could muster he pulled the space-suited figure away with him. Urteil's suit-light glimmered, and his power-unit gauge showed itself as not quite empty. The temperature inside his suit should return to normal quickly.

Bigman called the Dome. There was no other decision possible now. In their weakened condition, with their power supply low, another encounter with Mer-curian life would kill them. And he would manage to protect Lucky's position somehow.

It was remarkable how quickly men reached them.

With two cups of coffee and a hot meal inside him and the Dome's light and heat all about him, Bigman's resilient mind and body put the recent horror into proper perspective. It was already only an unpleasant memory.

Dr. Peverale hovered about him with an air partly like that of an anxious mother, partly like that of a nervous old man. His iron-gray hair was in disarray. "You're sure you're all right, Bigman. No ill effects?"

"I feel fine. Never better," insisted Bigman. "The question is, Doc, how's Urteil?"

"Apparently he'll be all right." The astronomer's voice grew cold. "Dr. Gardoma has examined him and reported favorably on his condition."

"Good," said Bigman almost gloatingly.

Dr. Peverale said with some surprise, "Are you concerned for him?"

"You bet, Doc. I've plans for him."

Dr. Hanley Cook entered now, almost trembling with excitement. "We've sent men into the mines to see if we can round up any of the creatures. They're taking heating pads with them. Like bait to a fish, you know." He turned to Bigman. "Lucky you got away."

Bigman's voice rose in pitch and he looked outraged, "It wasn't luck, it was brains. I figured they were after straight heat most of all. I figured it was their favorite kind of energy. So I gave it to them."

Dr. Peverale left after that, but Cook remained behind, talking of the creatures, walking back and forth, bubbling with speculation. "Imagine! The old stories about the freezing death in the mines were true. Really true! Think of it! Just rocky tentacles acting as heat sponges, absorbing energy wherever they can make contact. You're sure of the description, Bigman?"

"Of course I'm sure. When you catch one, see for yourself."

"What a discovery."

"How come they were never discovered before?" asked Bigman.

"According to you, they blend into their environment. Protective mimicry. Then, too, they attack only isolated men. Maybe," his words grew quicker, more animated, and his long fingers intertwined and twisted with one another, "there is some instinct there, some rudimentary intelligence that kept them hidden and out of sight. I'm sure of it. It's a kind of intelligence that kept them out of our way. They knew their only safety was in obscurity, so they attack only single, isolated men. Then for thirty years or more no men appeared in the mines. Their precious kernels of unusual heat were gone, and yet they never succumbed to the temptation to invade the Dome itself. But when men finally appeared once more in the mines, that temptation was too great and one of the creatures attacked, even though there were two men there and not one. For them, that was fatal. They have been discovered."

"Why don't they go to the Sun-side if they want energy and they're all that intelligent?" demanded Big-man.

"Maybe that's too hot," said Cook at once.

"They took the blaster. It was red hot."

"The Sun-side may be too full of hard radiation. They may not be adapted to that. Or maybe there is another breed of such creature on the Sun-side. How can we know? Maybe the dark-side ones live on radioactive ores and on the coronal glow."

Bigman shrugged. He found such speculation unprofitable.

And Cook's line of thought seemed to change too. He stared speculatively at Bigman, one finger rubbing his chin rhythmically. "So you saved Urteil's life.'

"That's right."

"Well, maybe it's a good thing. If Urteil had died, they would have blamed you. Senator Swenson could have made it darned hot for you and for Starr and for the Council. No matter what explanation you gave, you would have been there when Urteil died, and that would have been enough for Swenson."

"Listen," said Bigman, moving about uneasily, "when do I get to see Urteil?"

"Whenever Dr. Gardoma says you may."

"Get him on the wire and tell him to say I can, then."

Cook's gaze remained fastened thoughtfully on the small Martian. "What's on your mind?"

And because Bigman had to make arrangements about the gravity, he explained some of his plan to Cook.

Dr. Gardoma opened the door and nodded to Bigman to enter. "You can have him, Bigman.," he whispered. "I don't want him."

He stepped out, and Bigman and Urteil were alone with one another once again.

Jonathan Urteil was a little pallid where stubble didn't darken his face, but that was the only sign of his ordeal. He bared his lips to a savage grin. "I'm in one piece, if that's what you've come to see."

"That's what I've come to see. Also to ask you a question. Are you still full of that drivel about Lucky Starr setting up a fake Sirian base in the mines?"

"I intend to prove it."

"Look, you cobber, you know it's a lie, and you're going to fake proof if you can. Fake it! Now I'm not expecting you to get on your knees to thank me for saving your life... "

"Wait!" Slowly Urteil's face flushed. "All I remember is that that thing got me first by surprise. That was accident. After that, I don't know what happened. What you say means nothing to me."

Bigman shrieked with outrage. "You smudge of space dust, you yelled for help."

"Where's your witness? I don't remember a thing."

"How do you suppose you got out?"

"I'm not supposing anything. Maybe the thing crawled away on its own. Maybe there was no thing at all. Maybe a rockfall hit me and knocked me out. Now if you came here expecting me to cry on your shoulders and promise to lay off your grafting friend, you're going to be disappointed. If you have nothing else to say, good-by."

Bigman said, "There's something you're forgetting. You tried to kill me."

"Where's your witness? Now if you don't get out, I'll pucker up and blow you out, midget."

Bigman remained heroically calm. "I'll make a deal with you, Urteil. You've made every threat you can think of because you're half an inch taller than I am and half a pound heavier, but you crawled the only time I made a pass at you."

"With a force-knife and myself unarmed. Don't forget that."

"I say you're yellow. Meet me rough and tumble, now. No weapons. Or are you too weak?"

"Too weak for you? Two years in the hospital and I wouldn't be too weak for you!"

"Then fight. Before witnesses! We can use the space in the power room. I've made arrangements with Hanley Cook."

"Cook must hate you. What about Peverale?"

"Nobody asked him. And Cook doesn't hate me."

"He seems anxious to get you killed. But I don't think I'll give him the satisfaction. Why should I fight a half-pint of skin and wind?"

"Yellow?"

"I said, why? You said you were making a deal."

"Right. You win, I don't say a word about what happened in the mines, what really happened. I win, you lay off the Council."

"Some deal. Why should I worry about anything you can say about me?"

"You're not afraid of losing, are you?"

"Space!" The exclamation was enough.

Bigman said, "Well, then?"

"You must think I'm a fool. If I fight with you before witnesses I'll be indicted for murder. If I lean a finger on you, you're squashed. Go find yourself another way to commit suicide."

"All right. How much do you outweigh me?"

"A hundred pounds," said Urteil contemptuously.

"A hundred pounds of fat," squeaked Bigman, his gnomish face screwed into a ferocious scowl. "Tell you what. Let's fight under Mercurian gravity. That makes your advantage forty pounds. And you keep your inertia advantage. Fair enough?"

Urteil said, "Space, I'd like to give you one smash, just to plaster your big mouth over your miserable little face."

"You've got your chance. Is it a deal?"

"By Earth, it's a deal. I'll try not to kill you, but that's as far as I'll go. You've asked for this, you've begged for it."

"Right. Now let's go. Let's go." And Bigman was so anxious that he hopped about as he talked, sparring a little with rapid birdlike motions of his fists. In fact, such was his eagerness for this duel that not once did he give a specific thought to Lucky nor suffer any presentiment of disaster. He had no way of telling that, some time before, Lucky had fought a more deadly duel than the one Bigman now proposed.

The power-level had its tremendous generators and heavy equipment, but it also had its broad level space suitable for gatherings of personnel. It was the oldest part of the Dome. In the first days, before even a single mine shaft had been blasted into Mercurian soil, the original construction engineers had slept on cots in that space between the generators. Even now it was still occasionally used for trifilm entertainment.

Now it served as a ring, and Cook, together with half a dozen or so technicians, remained dubiously on the side lines.

"Is this all?" demanded Bigman.

Cook said, "Mindes and his men are out Sun-side. There are ten men in the mines looking for your ropes, and the rest are mostly at their instruments." He looked apprehensively at Urteil and said, "Are you sure you know what you're doing, Bigman?"

Urteil was stripped to the waist. He had a thick growth of hair over his chest and shoulders, and he moved his muscles with an athletic joy.

Bigman looked in Urteil's direction indifferently. "All set with the gravity?"

"We'll have it off at the signal. I've rigged the controls so the rest of the Dome won't be affected. Has Urteil agreed?"

"Sure." Bigman smiled. "It's all right, pal."

"I hope so," said Cook fervently.

Urteil called out, "When do we get started?" Then looking about the small group of spectators, he asked, "Anyone care to bet on the monkey?"

One of the technicians looked at Bigman with an uneasy grin. Bigman, now also stripped to his waist, looked surprisingly wiry, but the difference in size gave the match a grotesque appearance.

"No bet here," said the technician.

"Are we ready?" called Cook.

"I am," said Urteil.

Cook licked his pale lips and flicked the master switch. There was a change in the pitch of the subdued droning of the generators.

Bigman swayed with the sudden loss of weight. So did all the rest. Urteil stumbled but recovered rapidly and advanced gingerly into the middle of the clear space. He did not bother to lift his arms but stood waiting in a posture of complete relaxation.

"Start something, bug," he said.