Kallner was once again a-gleam in dress uniform. His white gloves shone as he shook hands.

Calvin said, “The other modified Nestors are, of course, to be destroyed.”

“They will be. We’ll make shift with normal robots, or, if necessary, do without.”

“Good.”

“But tell me— You haven’t explained— How was it done?”

She smiled tightly, “Oh, that. I would have told you in advance if I had been more certain of its working. You see, Nestor 10 had a superiority complex that was becoming more radical all the time. He liked to think that he and other robots knew more than human beings. It was becoming very important for him to think so.

“We knew that. So we warned every robot in advance that gamma rays would kill them, which it would, and we further warned them all that gamma rays would be between them and myself. So they all stayed where they were, naturally. By Nestor 10’s own logic in the previous test they had all decided that there was no point in trying to save a human being if they were sure to die before they could do it.”

“Well, yes, Dr. Calvin, I understand that. But why did Nestor 10 himself leave his seat?”

“Ah! That was a little arrangement between myself and your young Mr. Black. You see it wasn’t gamma rays that flooded the area between myself and the robots—but infrared rays. Just ordinary heat rays, absolutely harmless. Nestor 10 knew they were infrared and harmless and so he began to dash out, as he expected the rest would do, under First Law compulsion. It was only a fraction of a second too late that he remembered that the normal NS-2’s could detect radiation, but could not identify the type. That he himself could only identify wave lengths by virtue of the training he had received at Hyper Base, under mere human beings, was a little too humiliating to remember for just a moment. To the normal robots the area was fatal because we had told them it would be, and only Nestor 10 knew we were lying.

“And just for a moment he forgot, or didn’t want to remember, that other robots might be more ignorant than human beings. His very superiority caught him. Good-by, general.”

7. ESCAPE!

WHEN SUSAN CALVIN returned from Hyper Base, Alfred Lanning was waiting for her. The old man never spoke about his age, but everyone knew it to be over seventy-five. Yet his mind was keen, and if he had finally allowed himself to be made Director-Emeritus of Research with Bogert as acting Director, it did not prevent him from appearing in his office daily.

“How close are they to the Hyperatomic Drive?” he asked.

“I don’t know,” she replied irritably, “I didn’t ask.”

“Hmm. I wish they’d hurry. Because if they don’t, Consolidated might beat them to it. And beat us to it as well.”

“Consolidated. What have they got to do with it?”