"Right."

"But I notice you didn't say anything about when they did it," Albrecht pointed out.

"No, I didn't. That's where the 'never deal in dead certainties' I mentioned above comes in. There's a possibility—a very tiny possibility—that they could have recorded this ahead of time and then substituted that recording for the live imagery from the tower's owners' security system. But given the security protocols which would have to be circumvented, pulling it off—and especially pulling it off without getting caught at it—would be . . . extremely difficult, shall we say."

Albrecht rubbed his jaw thoughtfully.

"By all accounts, Zilwicki is very good at that sort of thing," he pointed out.

"Yes, and the accounts are accurate, too. But pulling off something like your suggesting would have meant meant getting into that bizarre virtual world where hackers have been jousting for over two thousand T-years." Collin made a "brushing away" gesture with his working hand. "Any security protocols can be circumvented, Father . . . and any program to circumvent security protocols can be detected. Then that detection can be circumvented, but the circumvention can be detected, and so on. It goes on literally forever. In the end, it comes down to the simple question of 'Are our cyberneticists as good as their cyberneticists?' "

Collin shrugged.

"I can't rule out the possibility that Zilwicki is—was—better at this than any—or, for that, matter all of—our people are. Frankly, it seems vanishingly unlikely that one man, no matter how good he may be, is going to be better than an entire planet's worth of competing cyberneticists. Still, I'll grant the possibility. But no matter how good he may have been, he was still playing in our front yard. If we'd been playing on his territory, I'd feel a lot less comfortable with our conclusions, but could Anton Zilwicki, using only the equipment and software he was able to smuggle onto Mesa—or obtain on the black market once he got here—get around the best protocols we've ever been able to create, with all the advantages of operating on our own home planet, and do it so seamlessly that we can't find a single trace of it?"

He shook his head.

"Yes, it's theoretically possible, but, in the real world, I really don't think it's likely at all." He pointed at the tiny, moving figures of the recorded imagery once more. "I think we're looking at what really happened and when it happened. Anton Zilwicki and Victor Cachat and an unknown female were passing through the parking facilities of what used to be the Benaventura Tower when someone set off a two-point-five kiloton nuclear device. The center of the explosion was about thirty meters from what you're seeing right this minute."

"Which, of course, explains the absence of any DNA traces." Benjamin made a face. "They were simply vaporized."

"Oh, there were plenty of DNA traces in the area." Collin chuckled harshly. "Even in that location, and even at that time on a Saturday morning, there had to be somebody around. Benaventura's been standing empty long enough, and it's far enough out into that industrial belt between the city proper and the spaceport, that traffic was thankfully light. In fact, that's almost certainly the reason Zilwicki and Cachat had chosen that particular route for their escape. Despite that, our best estimate from our pattern analysis of all of the tower's security recordings from the last couple of months or so is that there were probably at least thirty or forty people in the immediate vicinity. We've recovered over twenty complete and partial bodies, some of them pretty well incinerated, but we're positive there are quite a few we'll never know about.

"But the truth is that even if they hadn't been, for all practical purposes, right at the center of the fireball, we still wouldn't have gotten much from DNA analysis. Cachat is—was—a Havenite, born in Nouveau Paris itself, and StateSec did a pretty fanatical job of eliminating any medical records that might ever have existed when Saint-Just tapped him for special duties. No way we could get our hands on a sample we knew was his DNA. We'd have a better chance of getting a sample of Zilwicki's DNA, but he was from Gryphon. Nouveau Paris' population is an incredible stew, from everywhere, and Gryphon's population's genetic makeup isn't particularly distinct, either, so we couldn't even narrow an otherwise unidentified trace to either planet. We might have had a chance of identifying the Scrag—generically, at least—but even then only if she'd been a lot farther from the hypocenter. Ground zero, I should say. Technically, 'hypocenter' applies only to air bursts."

"All right," said Albrecht. "I'm persuaded . . . mostly." It was obvious to both his sons that the qualifier was pure spinal reflex on his part. "Now the question is: who set off the bomb?" Albrecht nodded at the hologram. "None of these people look to me like they were planning on committing suicide." He shook his head. "They were obviously going somewhere, and they were obviously in a hurry, even if they weren't exactly fleeing for their lives in panic. If they'd meant to kill themselves, then why go anywhere? And if they'd had even a clue a nuclear charge was about to go off less than fifty meters away, then I'd think they would have been going elsewhere a hell of a lot faster than they actually were!"

"We don't think they did it, Father. The possibility can't be ruled out, but we can't see any motivate they might've had to suicide. And as you say"—he nodded at the hologram himself—"that's definitely not the body language of people about to kill themselves, either."

"If not them, then who?" Benjamin asked.

"I doubt if we'll ever know, for sure," Collin replied. "Our best guess, after chewing on it for quite some time, is that Jack killed them."

"McBryde?" Albrecht frowned. "But why . . . Oh. You think he thought—correctly or otherwise—that Cachat and Zilwicki had doublecrossed him?"

"That's one explanation, yes—and the one that's favored by most of my team. This scenario is that Jack was trying to defect with Simões but the negotiations broke down. Probably because Cachayt and Zilwicki decided they'd already gotten enough from him to make leaving Mesa worthwhile and that smuggling him and Simões off-planet wasn't worth the risk."

"And McBryde suspected they might try that, and had laid that device ahead of time. And used a nuclear device—talk about overkill!—because he figured it would help eliminate anything that might be traced back to him." Again, Albrecht rubbed his jaw. "But how would he get them to be there at the right time?"

"Who knows? Keep in mind that he didn't have to finagle them into being there at any specific, preset time. Someone with Jack's training and experience could easily have set up a method of remote detonation, and there are several ways he could have known what escape route they'd be taking, even if he couldn't predict ahead of time when they'd be going through it. So he could have set the charge purely as an insurance policy. Then, once he knew he was going to execute Scorched Earth, he could have linked that detonation to the one in the tower. They happened almost simultaneously, after all."

"In other words, he took his revenge before he checked out himself."

"Or at the same time, you could say." Collin raised his right hand. "Father, the truth is that, given the havoc Jack wreaked on our computer systems and records, and the fact that Lajos Irvine is the only one of the central players who survived, we'll never know all of what happened, or exactly the reason why. All I can give you is the best assessment my people could come up with after a very long, thorough, exhaustive analysis."

He leaned forward and switched off the memo pad.