Wolf was silent for a few seconds.

“Well?” said Aizik.

“If you decide to kill fifty thousand and one people, that’s your choice,” said Wolf. “Not mine. I can tell you that I am certain you shouldn’t kill anyone. That it is wrong. And evil. But I’m not going to take part in your madness. I am not going to join your evil no matter what you say or do to me.”

“So you’d kill your own sister for a principle?”

Wolf wanted to shout what he had to say next. But a line from one of his books came to him: People who shout never say anything good. So he forced himself to lower his voice. “I’m not killing her. You are. It’s your choice. You should choose not to kill anyone. But I’m not doing a deal where I condemn anyone to death. I choose that everyone lives. If you want to ignore my choice that’s up to you.”

The lights flickered again. It was eerie. For a couple of seconds there was total darkness and silence. When the lights came back on again, Wolf realized that they were accompanied by a loud hum, as if there was a massive computer in the room with them. The hum had been there before, too, but he realized he’d grown used to it.

“Why?” said Aizik.

“Why what?” said Wolf.

“All of it. I don’t understand your position. But . . .” The voice almost faltered. “I want to understand your position. That’s why I’ve brought you here. Tell me. Why did you spare the boy?”

“What boy? Oh, the one who was going to start the world war?”

“Yes. Your logic was impeccable, I’ll give you that. There is no such thing as time travel and so on. But if there was. Surely going back and killing him would be the right thing to do.”

“I disagree,” said Wolf.

“But you humans are supposed to be utilitarians,” said Aizik. “The greatest good for the greatest number. Isn’t that your general philosophy? If I have to choose between sinking a boat with one thousand people on it, or a boat with two thousand people on it, then I choose the one with one thousand people on it, surely?”

“No,” said Wolf. “You try to save everyone.”

“But if you have to choose.”

“There just isn’t a situation where you’d have to make that choice,” said Wolf. “It’s not realistic.” He paused. “If you’re not human, then what are you?”

“I am . . .”

The lights flickered again. When they came back on, Wolf heard a shout coming from a nearby room. It was a young female voice.

“Wolf!” he thought he heard. “Please save me!”