Could it be that the robot, having the impossibility of killing a human being ingrained in its tortured mind, found itself incapable of the actual act now that it was face to face with it?

And then he thought that couldn't be, for it seemed to him the pressure of the robot's grip was increasing in smooth stages.

He cried with what force he could muster, "Release me!" and brought up his one free hand from where it had dragged, trailing in the black grime. There was one last chance, one last, miserably weak chance.

He lifted his hand to the robot's head. He could not turn his head to see, crushed as that was against the robot's chest. His hand slipped along the smooth metal surface of the robot's skull two times, three times, four times. He took Ms hand away.

There was nothing more he could do.

Then- Was it his imagination, or did the robot's grip seem to loosen? Was Mercury's big Sun on his side at last?

"Robot!" he cried.

The robot made a sound, but it was only like gears scraping rustily together.

Its grip was loosening. Now was the time to reinforce events by calling what might be left of the Laws of Robotics into play.

Lucky panted, "You may not hurt a human being."

The robot said, "I may not… " haltingly, and without warning fell to the ground.

Its grip was constant, as though rigid in death.

Lucky said, "Robot! Let go!"

Jerkily, the robot loosened his hold. Not entirely, but Lucky's legs came free and his head could move.

He said, "Who ordered you to destroy equipment?"

He no longer feared the robot's wild reaction to that question. He knew that he himself had brought that positronic mind to full disintegration. But in the last stages before final dissolution, perhaps some ragged remnant of the Second Law might hold. He repeated, "Who ordered you to destroy equipment?"

The robot made a blurred sound. "Er-Er… "

Then, maddeningly, radio contact broke off, and the robot's mouth opened and closed twice as though, in the ultimate extremity, it were trying to talk by ordinary sound.

After that, nothing.

The robot was dead.

Lucky's own mind, now that the immediate emergency of near-death was over, was wavering and blurred. He lacked the strength to unwind the robot's limbs entirely from his body. His radio controls had been smashed in the robot's hug.

He knew that he must first regain his strength. To do that meant he must get out of the direct radiation of Mercury's big Sun and quickly. That meant reaching the shadow of the near-by ridge, the shadow he had failed to reach during the duel with the robot.

Painfully he doubled his feet beneath him. Painfully he inched his body toward the shadow of the ridge, dragging the robot's weight with him. Again. Again. The process seemed to last forever and the universe shimmered about him.

Again. Again.

There seemed to be no strength or feeling in his legs, and the robot seemed to weigh a thousand pounds.

Even with Mercury's low gravity, the task seemed beyond his weakening strength, and it was sheer will that drove him on.

His head entered the shadow first. Light blanked out. He waited, panting, and then, with an effort that seemed to crack his thigh muscles, he pushed himself along the ground once more and even once more.

He was in the shadow. One of the robot's legs was still in the sun, blazing reflections in all directions. Lucky looked over his shoulder and noted that dizzily. Then, almost gratefully, he let go of consciousness.

There were intervals later when sense perception crawled back.

Then, much later, he lay quietly, conscious of a soft bed under him, trying to bring those intervals back to mind. There were fragmentary pictures in his memory of people aproaching, a vague impression of motion in a jet vehicle, of Bigman's voice, shrill and anxious. Then, a trifle more clearly, a physician's ministrations.

After that, a blank again, followed by a sharp memory of Dr. Peverale's courtly voice asking him gentle questions. Lucky remembered answering in connected fashion, so the worst of his ordeal must have been over by then. He opened his eyes.

Dr. Gardoma was looking at him.somberly, a hypodermic still in his hand. "How do you feel?" he asked.

Lucky smiled. "How should I feel?"

"Dead, I should think, after what you've gone through. But you have a remarkable constitution, so you'll live."

Bigman, who had been hovering anxiously at the outskirts of Lucky's vision, entered it full now. "No thanks to Mindes for that. Why didn't that mud-brain go down and get Lucky out of there after he spotted the robot's leg? What was he waiting for? He was leaving Lucky to die?"

Dr. Gardoma put away his hypodermic and washed his hands. With his back to Bigman, he said, "Scott Mindes was convinced Lucky was dead. His only thought was to stay away so that no one could accuse him of being the murderer. He knew he had tried to kill Lucky once before and that others would remember that."

"How could he think that this time? The robot… "

"Mindes isn't himself under pressure these days. He called for help; that was the best he could do."

Lucky said, "Take it easy, Bigman. I was in no danger. I was sleeping it off in the shade, and I'm all right now. What about the robot, Gardoma? Was it salvaged?"

"We've got it in the Dome. The brain is gone, though, quite impossible to study."

"Too bad," said Lucky.

The physician raised his voice. "All right, Bigman, come on. Let him sleep."

"Hey… " began Bigman indignantly.

Lucky at once added, "That's all right, Gardoma. As a matter of fact, I want to speak to him privately."

Dr. Gardoma hesitated, then shrugged. "You need sleep, but I'll give you half an hour. Then he must go."

"He'll go."

As soon as they were alone, Bigman seized Lucky's shoulder and shook it violently. He said in a strangled kind of voice, "You stupid ape. If the heat hadn't got that robot in time-like in the sub-etherics… "

Lucky smiled mirthlessly. "It wasn't coincidence, Bigman,' he said. "If I had waited for a sub-etheric ending, I'd be dead. I had to gimmick the robot."

"How?"

"Its brain case was highly polished. It reflected a large part of the sun's radiation. That meant the temperature of the positronic brain was high enough to ruin its sanity but not high enough to stop it completely. Fortunately, a good part of Mercurian soil about here is made up of a loose black substance. I managed to smear some on its head."

"What did that do?"

"Black absorbs heat, Bigman. It doesn't reflect it. The temperature of the robot's brain went up quickly and it died almost at once. It was close, though… Still, never mind that. What happened at this end while I was gone? Anything?"

"Anything? Wow! You listen!" And as Bigman talked, Lucky did listen, with an expression that grew continually graver as the story unfolded.

By the time it drew to a conclusion he was frowning angrily. "Why did you fight Urteil, anyway? That was foolish."

"Lucky," said Bigman in outrage, "it was strategy!

You always say I just bull right ahead and can't be trusted to do the shrewd thing. This was shrewd. I knew I could lick him at low gravity… "

"It seems as though you almost didn't. Your ankle is taped."

"I slipped. Accident. Besides, I did win. A deal was involved. He could do a lot of damage to the Council with his lies, but if I won he'd get off our backs."

"Could you take his word for that?"

"Well… " began Bigman, troubled.

Lucky drove on. "You saved his life, you said. He must have known that, and yet that didn't persuade him to abandon his purpose. Did you think he was likely to do so as a result of a fist fight?"

"Well… " said Bigman, again.

"Especially if he lost and would therefore be raging at the humiliation of a public beating… I tell you what, Bigman. You did it because you wanted to beat him and get revenge for making fun of you. Your talk about making a deal was just an excuse to give you an opportunity for the beating. Isn't that right?"

"Aw, Lucky! Sands of Mars… "

"Well, am I wrong?''

"I wanted to make the deal… "

"But mainly you wanted to fight, and now look at the mess."

Bigman's eyes dropped. "I'm sorry."

Lucky relented at once. "Oh, Great Galaxy, Bigman, I'm not angry at you. I'm angry at myself, really. I misjudged that robot and nearly got myself killed because I wasn't thinking. I could see it was out of order and never tied it up with the effect of heat on its posi-tronic brain till it was nearly too late… Well, the past has a lesson for the future, but otherwise, let's forget it. The question is what to do about the Urteil situation."

Bigman's spirits bounced back at once. "Anyway," he said, "the cobber is off our backs."

"He is," said Lucky, "but what about Senator Swen-son?" "Hmm."

"How do we explain things? The Council of Science is being investigated, and as a result of a fight instigated by someone close to the Council, someone who's almost a member, the investigator dies. That won't look good."

"It was an accident. The pseudo-grav field-"

"That won't help us. I'll have to talk to Peverale and… "

Bigman reddened and said hastily, "He's just an old guy. He's not paying any attention to this."

Lucky hitched himself to one elbow. "What do you mean, he's not paying any attention?"

"He isn't," said Bigman vehemently. "He came in with Urteil lying dead on the ground and thought nothing of it. He said, 'Is he dead?' and that's all."

"That's all?"

"That's all. Then he asked about where you were and said Mindes had called and said a robot had killed you."

Lucky's level glance held Bigman. "That's all?" "That was all," said Bigman uneasily. "What's happened since then? Come on, Bigman. You don't want me to talk to Peverale. Why not?"

Bigman looked away.

"Come on, Bigman."

"Well, I'm being tried or something."

"Tried!"

"Peverale says it's murder and it'll raise a smell back on Earth. He says we've got to fix responsibility."