“Tara’s going through a hard time. But she’s the best we have. Not only is she chief security tech — which gives her access to every system — but she’s unique in having worked both the security and computer engineering sides of the company.”

“If she gets with the program.”

Mauchly’s cell phone went off, and he quickly raised it. “Mauchly.” A pause. “Yes, of course, sir. Right away.”

He replaced the cell phone. “That was Silver. He wants to see us, and right now.”

The day had grown dark and overcast, and the elevator doors opened onto a view far different than Lash had witnessed the day before. Only a handful of the cut-glass ceiling fixtures threw small pools of light across the vast room. Beyond the windows lay a gray stormscape of skyscrapers. The museum-like collection of thinking machines lay before them, hulking objects set against a lowering sky.

Richard Silver was standing by the bank of windows, hands clasped behind his back. At the elevator’s chime he turned.

“Christopher,” he said, shaking Lash’s hand. “Nice to see you again. Something to drink?”

“Coffee would be nice.”

“I’ll get it,” said Mauchly, moving toward a wet bar set into one of the bookcases.

Silver motioned Lash to the same table they’d sat at the day before. The magazines and newspapers were gone. Silver waited for Lash to sit, then took a chair across from him. He was wearing corduroys and a black cashmere sweater, sleeves pulled up his forearms.

“I’ve thought a lot about what you told me yesterday,” he said. “About these deaths not being suicide. I didn’t want to believe it. But I think you were right.”

“I don’t see any other possibility.”

“No, I didn’t mean that. I meant what you said about Eden being involved, either way.” Silver looked past Lash, his expression troubled. “I’ve been too wrapped up in my own projects, here in my ivory tower. I’ve always been more fascinated by pure science than applied science. Trying to build a machine that can think, learn, solve problems on its own: that’s where my heart’s always been. Exactly what problems interested me less than the capability of solving them. It wasn’t until the idea for Eden came along that I grew personally involved. Finally, a task to which Liza was worthy: human happiness. Even so, I’ve kept removed from the day-to-day process. And I see now this was a mistake.”

Silver stopped, his gaze focused again on Lash. “I’m not sure why I’m telling you this.”

“People tell me I’ve got a face that inspires confidences.”

Silver laughed quietly. “Anyway, I finally decided that, if I’ve been uninvolved in the past, there was something I could do. Now.”

“What’s that?”

Mauchly returned, coffee in hand, and Silver stood. “If you’ll come with me?”

He led the way to a far corner, where the glass windows that ran around three sides of the room met the bookcases of the fourth. Here, Silver’s collection of computing machines appeared to run to the musical: a Farfisa Combo; a Mellotron; and a modular Moog synthesizer, all patch cords and low-pass filters.

Silver turned to him. “You said the killer was most likely a rejected Eden candidate.”

“That’s what the profile suggests. Perhaps a schizoid personality that couldn’t accept rejection. There’s a smaller chance the killer dropped out of the program after acceptance. Or was one of those clients not matched within your five-cycle window.”

Silver nodded. “I instructed Liza to parse all accessible applicant data, looking for anomalies.”

“Anomalies?”

“It’s a little hard to explain. Imagine creating a virtual topology in three dimensions, then populating it with applicant data. Compress the data, compare it. It’s almost like the avatar matching Liza does every day, done in reverse. See, our applicants have already been psychologically vetted; they should all skew to tightly bounded norms. I was looking for applicants whose behavior, personality, lie outside those norms.”

“Deviants,” Lash said.

“Yes,” Silver looked pained. “Or people whose behavior patterns were out of sync with their evaluations.”

“How did you do this so quickly?”

“Actually, I didn’t. I instructed Liza on the nature of the problem, and she developed the methodology on her own.”

“Using the data from applicant testing?”

“Not only that. Liza also called on data trails left by rejected applicants and voluntary dropouts in the months or years since their original applications.”

Lash was shocked. “You mean, data gathered after they weren’t potential clients anymore? How is such a thing possible?”

“It’s called activity monitoring. It’s practiced by many large corporations. The government does it, too. We’re just a few years ahead of everybody else. Mauchly’s probably shown you some of its elementary uses already.” Silver smoothed the front of his sweater. “In any case, Liza flagged three names.”

“Flagged? As in, already?”

Silver nodded.

“But there must have been a tremendous amount of data—”

“Approximately half a million petabytes. It would have taken a Cray a year to parse. Liza completed it in hours.” And he gestured at something near the wall.

Lash stared with fresh amazement at something he’d assumed was another antique from Silver’s collection. A standard computer keyboard sat on a small table, before an old-fashioned monochrome VDT terminal. A printer stood to one side.

“This is it?” Lash said incredulously. “This is Liza?”

“What did you expect?”

“I didn’t expect this.”

“Liza herself, or her computational plant, occupies the floors directly below us. But why make an interface more complicated than it has to be? You’d be surprised how much I can accomplish with just this.”

Lash thought about the computing feat Liza had just completed. “No, I wouldn’t.”

Silver hesitated. “Christopher, you’d mentioned another possibility. That the killer was somebody on our own staff. So I also instructed Liza to search for anything unusual, internally.” His expression grew tight, as if in physical pain. “She flagged one name.”

Silver turned to the small table, picked up two sheets of folded paper, and pressed them into Lash’s hand.

“Good luck — if that is indeed the right word.”

Lash nodded, turned to go.

“Christopher? One other thing.”

Lash glanced back.

“I know you understand why I gave this Liza’s highest priority.”

“I do. And thanks.”

He let Mauchly lead the way to the elevator, considering Silver’s last words. The same thought had also been running through his own head. The Thorpe couple had died on a Friday, eleven days before. The Wilners had died the following Friday. Serial killers liked consistency and pattern.

They had three days.

Four names,” Mauchly said.

He was staring at the table in Lash’s office. The two sheets of paper Silver provided lay on it, unfolded.

“Any idea why Liza flagged these four in particular?” Tara asked from across the table.

Mauchly picked up the sheet on which a single name had been printed. “Gary Handerling. Doesn’t ring a bell.”

“He’s part of the scrub crew,” Tara said.

“The what?” said Lash.

“Data scrub. They’re in charge of data storage and security.”

Mauchly glanced at her. “You’ve started the internal trace on him?”

“It should be completed within twelve hours.”

“Highest degree of confidentiality?”

“Of course.”

“Then I’d better get started on the three clients.” Mauchly picked up the other sheet. “I’ll have Rumson in Selective Gathering do complete workups.”

“What’ll you tell him?” Tara asked.

“That we’re running some random prototyping on a few obsoletes. Just another system test.”