The Phylaxis Group offices occupied three floors of a refurbished small industries complex in the Lincoln District, just off the Seventeenth Corridor. They were crowded between a modest heavy metals recovery business and a recently abandoned tailoring shop. The air always faintly smelled of hot ozone and acid. A small plaque by the main entrance identified the Group headquarters, but they received no walk-in business. Derec had put in a reception area when he had gotten the permits, but it had been a gesture, a visible symbol of what he had hoped would become more than just a promise among politicians. As he walked through the empty front office, he doubted any of his hopes would come true. Earth would surely reject all positronics now. And if not, the Fifty Worlds had no reason to try to continue relations with them.

When he entered the main lab, Rana turned from her console and grinned at him proudly. She was a compact woman, with close-cropped black curls and narrow hazel eyes. "I made a duplicate," she said. "We still have an RI matrix to study."

Derec stared at her, uncomprehending. "A copy… how-?"

"While the transfer to their buffer was going on. It was simple to just assign a secondary address."

Derec laughed. "It's not traceable, is it?"

"Please, Derec. Credit me with some sophistication. I didn't want to say anything over the com earlier, just in case. You mentioned Special Service, and I just don't trust those"

"They're not that bad. "

"With all due respect, Derec, you don't trust them either, otherwise you wouldn't have 'forgotten' that you were on com with me when they showed up."

He sobered, thinking of the two agents arriving at the med facility-the same pair that had thrown him out of Union Station. No, he did not trust them, but he doubted they had tapped his comlines. But perhaps Rana's caution would not be a bad example to follow until they knew more.

"Well. In that case," he said, "make another duplicate and hide it, just in case we get an on-site visit."

"Already working on it. "

"Start a forensic. There's an isolated segment in the RI where the recorded perceptions deviate radically from reality. We need to know how that happened."

"Deviated in what way?"

"I don't know. The roboticists on site told me it was a strategy game, but it looked like a full sensory hallucination. Thales?"

"Yes, Derec?" the smooth, disembodied voice of their RI answered.

"I want you to run a diagnostic through Union Station while you're in there. See if you can find any irregularities in the support systems, comlines-anything that's connected to the RI."

"Do you have a specific irregularity in mind, Derec?"

"No… the RI started playing a strategy game called Coup when it went off-line. See if there's anything about it in the regular datum files."

"Yes, Derec."

"Hallucination?" Rana said. "That's impossible."

"Of course it is. Everyone knows positronic brains can't hallucinate. But this one did. Did you get hold of our attorney?"

"No, he's in Chicago Sector. I left a message for him to call us in the morning. Have you called anyone else about this? We're supposed to be doing all the troubleshooting on a positronic brain."

"Who would you have me call? I tried the subcommittee, but I only spoke to Vann and Hajer, and they didn't know anything about this."

"What about what's-his-name?" Rana asked. "Taprin?"

Derec shook his head. "He's doubtless up to his hairline in Clar's death. I won't bother him unless I have to. I'd rather talk to our lawyer, but I suppose morning will have to do. What about this RI? Have you given it a look yet?"

"It's a jumbled mess. I already found the collapse points, but we have a major problem."

Derec glanced at Rana, who glared at her screen. She stabbed at a couple of keys on her board, then sat back, sucking her lower lip under her teeth. Derec waited.

"It went into nearly complete collapse once it came back online." She jabbed a finger at the screen. "Here and here you can see the recursive loops it generated while trying to cope with the situation. They spiralled out of control as more data came available, and it reached the inescapable conclusion that it was responsible for the deaths of humans. Total First Law violation. It followed its own navel into oblivion."

"No one ordered it to shut down," Derec said.

"Evidently not. It just didn't occur to anyone to think to preserve whatever data the RI might have."

"Or they assumed that collapse meant stasis."

Rana cocked an eyebrow at him. "Oh, sure, just like a human mind remains orderly during a psychotic break."

"Well, it does, sort of. The point is, a positronic brain isn't a human brain, so the expectation is unrealistic. But most people don't know that." Derec studied the screens. "This looks worse than it should, though. There ought to have been discreet sectors, at least. This appeared to have no coherence at all."

"You said there were two positronic specialists there?" Rana said.

"They were there when I arrived. Whether or not they were on watch when this happened…"

The pattern on their screens resembled a collection of interference grids, moirй textures, coils, dark and light alternating rhythmically. Rana touched a spot on her screen.

"What bothers me are these little loops here and here. Same sort of thing, but according to their size they never quite amounted to much, like a problem that solved itself. Now, that can theoretically happen in a positronic brain-confusion, ambiguity, indecision, all that can start a recursive loop that dissolves as soon as it finds solid footing. But not this much, and they usually have a distinctive endpoint pattern. These just evaporate…"

"It's likely the same event could trigger several loops."

"Sure."

"Of which only one or two develop into collapse."

"It depends, though, doesn't it?"

"On?"

Rana scratched at her chin absently, eyes wide, lost in the configurations before her. Derec waited. She had been his best student on Earth. She grasped positronics better than anyone else he had trained here, but she still had to think her way through certain concepts that seemed to come naturally to him, or for that matter any positronic specialist from a Spacer world. It was said that one needed to be raised in the discipline to be good at it; Rana had proved that axiom false, but she still wrestled with it like a second language.

He wondered where Kedder and Hammis had gotten their training…

"Depends on when these loops developed," she said finally. "Their location and configuration suggest that they happened earlier than these major loops. It's hard to tell. Chronology in a collapsed positronic matrix is as jumbled as everything else. But if they're earlier, then I'd like to know what triggered them."

"Wouldn't it be more to the point to find out why it took itself off-line to playa game?"

"Those loops could be tied to that."

Derec nodded. It made sense. At least he hoped it did. He suddenly realized how very tired he was and glanced at the time chop on one of the screens. Eighteen hours since he had started the day. Rana had been up longer, but she still appeared alert and engaged. Having a problem to solve energized her.

"Okay," he said, "you work on those. I need to sleep."

"I'll call you."

Derec stood and looked around the room. Equipment covered the walls around them. Stations for eight people-all empty but for the two chairs Rana and he used-spoke of the ambitions of the Group more than the reality. Of the handful of qualified roboticists on Earth, Phylaxis employed four. All the other people he employed, field operatives, office personnel, and paralegals-twelve in all-were little more than eager amateurs. This room contained facilities to keep eight roboticists busy full time-given a commensurate workload. The treaty conference would have provided that work with a successful outcome.

"I'll be upstairs," he said, and left.

Derec climbed to the small apartment he kept on the premises, his legs seeming to grow heavier.

The room contained a bed, a datum, comlink, a shower and toilet, a small closet, and its own food synthesizer. It was only slightly larger than a decent cabin on a starship. Derec kept a bigger, better-appointed apartment a few kilometers away, but he often spent his nights here, even if he had nothing to do.

He sat down on the edge of the bed and rubbed his face with the heels of his hands.

Senator Clar Eliton, dead. He still could not take it in.

What about our charter? he wondered. Without Eliton to champion the entire robotics cause, Phylaxis could end up without a license. Not that it mattered, because without Eliton the reintroduction of positronics to Earth could very likely halt.

"Tomorrow," he told himself.

"You have several messages, Derec," Thales told him.

"List."

"Four from the Senate Select Committee on Machine Intelligence, two from the Committee on Import-Export, one from the Calvin Institute-"

"Stop. Play last one."

"Message reads: 'I see you got your wish. ' Message ends."

Derec sighed. "Ariel."

"The message was not signed," Thales noted.

"No, of course not."

"Would you like me to continue?"

"No. Store messages. I'll go through them… later."

So I got my wish, he thought. He lay back on the mattress. What might that be?

As much as he wanted to assume otherwise, he knew she meant Bogard. They had argued bitterly over it, she rejecting the idea of tampering with the Three Laws at any level. Robots, she believed, should be slaves, ideal servants, with only enough self-direction to interpret the inexactitudes of human commands and possibly anticipate human desires.

But to construct a robot that could circumvent one of the Three Laws, no matter how little or how briefly, went against everything she believed about robots. It came too close to free will for her.

Of all the things that might have driven a wedge between them, casuistry would have been the last thing Derec expected.