But Dum and Dee-and Soggdon-plainly had more on their minds than Kresh’s reaction to his own words. There was dead silence for a full thirty seconds before any of them reacted. The perfect holographic image of the Inferno of the future flickered and wavered and almost vanished altogether before it resolidified.

Unit Dee recovered first. “Am I to under-under-understand that you intend this as a serious idea?” she asked. The stress in her voice was plain, her words coming out with painful slowness.

“Not good,” said Soggdon, her headset mike still off. She turned toward a side console, paged through several screenfuls of information, and shook her head. “I warned you she took her simulants seriously,” she said. “These readings show you’ve set off a mild First Law conflict in her. You can’t just come in here and play games with her, make up things like that.”

Kresh cut his own mike. “I’m not making things up,” he said. “And I’m not playing games. There is a serious plan in motion to drop a fragmented comet on the Utopia region.”

“But that’s suicidal!” Soggdon protested.

“What difference does it make if the planet’s going to be dead in two hundred years?” Kresh snapped. “And as for Dee, I suggest it is time you start lying to her in earnest. Remind her it’s all a simulation, an experiment. Remind her that Inferno isn’t real, and no one will be harmed.”

“Tell her that?” Soggdon asked, plainly shocked. “No. I will not feed her dangerous and false data. Absolutely not. You can tell her yourself.”

Kresh drew in his breath, ready to shout in the woman’s face, give her the dressing-down she deserved. But no. It would do no good. It was plainly obvious that she was not thinking with the slightest degree of rationality or sense-and he needed her, needed her help, needed her rational and sensible. She was part of the team that had set up this charade. She was the one who would have to prop it up. He would have to reason with her, coolly, calmly. “It would do no good for me to tell her any such thing,” he said. “She thinks I’m a simulant. Simulants don’t know they are simulants. She would not believe me telling her there was no danger-because she does not believe me to be human. And she does not believe that because you have lied to her.”

“That’s different. That’s part of the experiment design. It’s not false data.”

“Nonsense,” Kresh said, a bit more steel coming into his voice as the gentleness left it. “You have set up this entire situation for the sole purpose of allowing her to take risks, to do her job, while believing she could no harm to humans.”

“But-”

Kresh kept talking, rolling right over her protests. “I could even do damage to her if I told her it was just a simulation. There must be some doubt in her mind as to whether her simulants-the people of Inferno-are real. Otherwise she would not be experiencing the slightest First Law conflict concerning them. If I assured her that I was not real, Space alone knows what she would make of that paradox. It seems to me as likely as not that she would reach the conclusion that I was real, and that I was lying to her. If I lie to her, she might realize the truth-and then where would you be, Dr. Soggdon? Only you can do it. Only you can reassure her. And you must do it.”

Soggdon glared at Kresh, the anger and fear plain on her face as she switched on her mike again. “Dee, this is Dr. Soggdon. I am still monitoring the simulation. I am detecting what appear to be First Law conflicts in the positronic pathing display. There is no First Law element to the simulated circumstances under consideration.” Soggdon hesitated, made a face, and then spoke again. “There is absolutely no possibility of harm to human beings,” she said. “Do you understand?”

There was another distinct pause, and Kresh thought he detected another, but much slighter, flicker in the image of the Inferno that was to be. But then Dee spoke again, and her voice was firm and confident. “Yes, Doctor Soggdon. I do understand,” she said. “Thank you. Excuse me. I must return to my conversation with the simulant governor.” Another pause, and then Dee was speaking to Kresh. “I beg your pardon, Governor. Other processing demands took my time up for the moment.”

“Quite all right,” Kresh said. Of course, Dee was no doubt linked to a thousand other sites and operations, and probably having a dozen other conversations with field workers right now. It was not quite a little white lie, but it was certainly close enough to being one. Robots were supposed to be incapable of lying-but this one was clever enough to manage a truthful and yet misleading statement. Dee was a sophisticated unit indeed.

“Can you tell me more about this…idea under discussion?” Dee asked him.

“Certainly,” said Kresh. “The idea is to evacuate everyone from the target area, and provide safeguards for the population outside the target area.” It could not hurt to emphasize safety procedures first off. Let her know that even the fictional simulants would be safe. They needed as many defenses as possible against a First Law reaction. “Once that is accomplished, a large comet is to be broken up and the fragments targeted individually, the overlapping craters running through existing lowlands. More conventional earth-moving will no doubt be required afterwards, but the linked and overlapping craters will form the basis for the Utopia Inlet.”

“I see,” Dee replied, her voice still strained and tense. “Unit Dum and I will require a great deal more information before we can evaluate this plan.”

“Certainly,” said Kresh. He pulled a piece of paper out of his tunic and unfolded it. “Refer to network access node 43l3, identity Davlo Lentrall, subgroup 9l9, referent code Comet Grieg.” Lentrall had given him the access address earlier. Now seemed the moment to put it to good use. “Examine the data there and you will be able to do your evaluations,” said Kresh.

“There is no identity Davlo Lentrall on access node 43l3,” Dee said at once.

“What?” said Kresh.

“No one named Davlo Lentrall is linked into that access node,” said Dee.

“The number must be wrong, or something,” said Kresh.

“Quite likely,” said Dee. “I’m going to hand off to Dum. He is directly linked to the network in question and can perform the search more effectively.”

“There is no Davlo Lentrall on node 4313,” Dum announced, almost at once, speaking in an even flatter monotone than usual. “Searching all net nodes. No Davlo Lentrall found. Searching maintenance archives. Information on identity Davlo Lentrall discovered.”

“Report on that information,” Kresh said. How could Lentrall’s files have vanished off the net? Something was wrong. Something was seriously and dangerously wrong.

“Network action logs show that all files, including all backups, linked to the identity Davlo Lentrall, were invasively and irrevocably erased from the network eighteen hours, ten minutes, and three seconds ago,” Unit Dum announced.

Kresh was stunned. He looked to Soggdon, not quite knowing why he hoped for an answer from that quarter. He switched off his mike and spoke to her. “I don’t understand,” he said. “How could it all be erased? Why would anyone do that?”

“I don’t know,” she said. “He used a term I’m not familiar with in this context. Let me check.” She keyed on her own mike again. “Dum, this is Soggdon, monitoring. Define meaning of the term ‘invasive’ in present situation.”

“Invasive-contextual definition: performed by an invader, an attack from the outside, the act of an invader.”

“In other words,” said Kresh, his voice as cold and hard as he could make it, “someone has broken in and deliberately destroyed the files. “ He suddenly remembered what Fredda had said, about the things you thought you knew. She had said something about never really being sure about what you knew. Here it was, happening again. He had thought he knew where the comet was. Now he knew he did not. “It would seem,” he said, “that someone out there agrees with you, Dr. Soggdon. They don’t want anyone playing with comets.”