Olham struggled out of his lethargy. "Can't you tell me -"

"Certainly, I'll tell you." Peters nodded. "Two days ago we received a report that an Outspace ship had penetrated the protec-bubble. The ship let off a spy in the form of a humanoid robot. The robot was to destroy a particular human being and take his place."

Peters looked calmly at Olham.

"Inside the robot was a U-Bomb. Our agent did not know how the bomb was to be detonated, but he conjectured that it might be by a particular spoken phrase, a certain group of words. The robot would live the life of the person he killed, entering into his usual activities, his job, his social life. He had been constructed to resemble that person. No one would know the difference."

Olham's face went sickly chalk.

"The person whom the robot was to impersonate was Spence Olham, a high-ranking official at one of the research Projects. Because this particular Project was approaching crucial stage, the presence of an animate bomb, moving toward the center of the Project -"

Olham stared down at his hands. "But I'm Olham."

"Once the robot had located and killed Olham it was a simple matter to take over his life. The robot was released from the ship eight days ago. The substitution was probably accomplished over the last weekend, when Olham went for a short walk in the hills."

"But I'm Olham." He turned to Nelson, sitting at the controls. "Don't you recognize me? You've known me for twenty years. Don't you remember how we went to college together?" He stood up,. "You and I were at the University. We had the same room." He went toward Nelson.

"Stay away from me!" Nelson snarled.

"Listen. Remember our second year? Remember that girl? What was her name -" He rubbed his forehead. "The one with the dark hair. The one we met over at Ted's place."

"Stop!" Nelson waved the gun frantically. "I don't want to hear any more. You killed him! You… machine."

Olham looked at Nelson. "You're wrong. I don't know what happened, but the robot never reached me. Something must have gone wrong. Maybe the ship crashed." He turned to Peters. "I'm Olham. I know it. No transfer was made. I'm the same as I've always been."

He touched himself, running his hands over his body. "There must be some way to prove it. Take me back to Earth. An X-ray examination, a neurological study, anything like that will show you. Or maybe we can find the crashed ship."

Neither Peters nor Nelson spoke.

"I am Olham," he said again. "I know I am. But I can't prove it."

"The robot," Peters said, "would be unaware that he was not the real Spence Olham. He would become Olham in mind as well as body. He was given an artificial memory system, false recall. He would look like him, have his memories, his thoughts and interests, perform his job.

"But there would be one difference. Inside the robot is a U-Bomb, ready to explode at the trigger phrase." Peters moved a little away. That's the one difference. That's why we're taking you to the Moon. They'll disassemble you and remove the bomb. Maybe it will explode, but it won't matter, not there."

Olham sat down slowly.

"We'll be there soon," Nelson said.

He lay back, thinking frantically, as the ship dropped slowly down. Under them was the pitted surface of the Moon, the endless expanse of ruin. What could he do? What would save him?

"Get ready," Peters said.

In a few minutes he would be dead. Down below he could see a tiny dot, a building of some kind. There were men in the building, the demolition team, waiting to tear him to bits. They would rip him open, pull off his arms and legs, break him apart. When they found no bomb they would be surprised; they would know, but it would be too late.

Olham looked around the small cabin. Nelson was still holding the gun. There was no chance there. If he could get to a doctor, have an examination made – that was the only way. Mary could help him. He thought frantically, his mind racing. Only a few minutes, just a little time left. If he could contact her, get word to her some way.

"Easy," Peters said. The ship came down slowly, bumping on the rough ground. There was silence.

"Listen," Olham said thickly. "I can prove I'm Spence Olham. Get a doctor. Bring him here -"

"There's the squad," Nelson pointed. "They're coming." He glanced nervously at Olham. "I hope nothing happens."

"We'll be gone before they start work," Peters said. "We'll be out of here in a moment." He put on his pressure suit. When he had finished he took the gun from Nelson. "I'll watch him for a moment."

Nelson put on his pressure suit, hurrying awkwardly. "How about him?" He indicated Olham. "Will he need one?"

"No." Peters shook his head. "Robots probably don't require oxygen."

The group of men were almost to the ship. They halted, waiting. Peters signaled to them.

"Come on!" He waved his hand and the men approached warily; stiff, grotesque figures in their inflated suits.

"If you open the door," Olham said, "it means my death. It will be murder."

"Open the door," Nelson said. He reached for the handle.

Olham watched him. He saw the man's hand tighten around the metal rod. In a moment the door would swing back, the air in the ship would rush out. He would die, and presently they would realize their mistake. Perhaps at some other time, when there was no war, men might not act this way, hurrying an individual to his death because they were afraid. Everyone was frightened, everyone was willing to sacrifice the individual because of the group fear.

He was being killed because they could not wait to be sure of his guilt. There was not enough time.

He looked at Nelson. Nelson had been his friend for years. They had gone to school together. He had been best man at his wedding. Now Nelson was going to kill him. But Nelson was not wicked; it was not his fault. It was the times. Perhaps it had been the same way during the plagues. When men had shown a spot they probably had been killed, too, without a moment's hesitation, without proof, on suspicion alone. In times of danger there was no other way.

He did not blame them. But he had to live. His life was too precious to be sacrificed. Olham thought quickly. What could he do? Was there anything? He looked around.

"Here goes," Nelson said.

"You're right," Olham said. The sound of his own voice surprised him. It was the strength of desperation. "I have no need of air. Open the door."

They paused, looking at him in curious alarm.

"Go ahead. Open it. It makes no difference." Olham's hand disappeared inside his jacket. "I wonder how far you two can run?"

"Run?"

"You have fifteen seconds to live." Inside his jacket his fingers twisted, his arm suddenly rigid. He relaxed, smiling a little. "You were wrong about the trigger phrase. In that respect you were mistaken. Fourteen seconds, now."

Two shocked faces stared at him from the pressure suits. Then they were struggling, running, tearing the door open. The air shrieked out, spilling into the void. Peters and Nelson bolted out of the ship. Olham came after them. He grasped the door and dragged it shut. The automatic pressure system chugged furiously, restoring the air. Olham let his breath out with a shudder.

One more second -

Beyond the window the two men had joined the group. The group scattered, running in all directions. One by one they threw themselves down, prone on the ground. Olham seated himself at the control board. He moved the dials into place. As the ship rose up into the air the men below scrambled to their feet and stared up, their mouths open. "Sorry," Olham murmured, "but I've got to get back to Earth." He headed the ship back the way it had come.

It was night. All around the ship crickets chirped, disturbing the chill darkness. Olham bent over the vidscreen. Gradually the image formed; the call had gone through without trouble. He breathed a sigh of relief.