"I am so sorry," T4S said. "Please believe that."

She didn"t answer. Pulling Janey close, Ca.s.sie rocked both her children until Janey quieted. Then she said softly, "I have to get water for Donnie, honey. He needs to stay hydrated." Janey clutched briefly but let her go.

Ca.s.sie drew a cup of water from the lab bench. At the same time, she picked up the vial of foodless bacteria. She forced Donnie to take a few sips of water; more might come back up again. He struggled weakly. She leaned over him, cradling and insisting, and her body blocked the view from the ceiling sensors when she dipped her finger into the vial and smeared its small amount of liquid into the back of her son"s mouth.

Throat tissues were the ideal culture for Streptococcus pyogenes. Under good conditions, they replicated every twenty minutes, a process that had already begun in vitro. Very soon there would be hundreds, then thousands of re-engineered bacteria, breeding in her child"s throat and lungs and drifting out on the air with his every sick, labored breath.

Morning again. Elya rose from fitful sleep on the back seat of an FBI car. She felt achy, dirty, hungry.

During the night another copter had landed on the lawn. This one had MED-RESCUE painted on it in bright yellow, and Elya looked around to see if anyone had been injured. Or-her neck p.r.i.c.kled-was the copter for Ca.s.sie and the children if Agent Bollman wacoed? Three people climbed down from the copter, and Elya realized none of them could be medtechs. One was a very old man who limped; one was a tall woman with the same blankly efficient look as Bollman; one was the pilot, who headed immediately for the cold pizza. Bollman hurried over to them. Elya followed.

"...glad you"re here, sir," Bollman was saying to the old man in his courteous negotiating voice, "and you, Ms. Arnold. Did you bring your records? Are they complete?"

"I don"t need records. I remember this install perfectly."

So the FBI-looking woman was a datalinker and the weak old man was somebody important from Washington. That would teach her, Elya thought, to judge from superficialities.

The datalinker continued, "The client wanted the central processor above a bas.e.m.e.nt room she was turning into a lab, so the cables could go easily through a wall. It was a b.i.t.c.h even so, because the walls are made of reinforced foamcast like some kind of bunker, and the outer walls have a Faraday-cage mesh. The Faraday didn"t interfere with the cable data, of course, because that"s all laser, but even so we had to have contractors come in and bury the cables in another layer of foamcast."

Bollman said patiently, "But where was the processor actually installed? That"s what we need to know."

"Northeast corner of the building, flush with the north wall and ten point two feet in from the east wall."

"You"re sure?"

The woman"s eyes narrowed. "Positive."

"Could it have been moved since your install?"

She shrugged. "Anything"s possible. But it isn"t likely. The install was b.i.t.c.h enough."

"Thank you, Ms. Arnold. Would you wait over there in case we have more questions?"

Ms. Arnold went to join the pilot. Bollman took the old man by the arm and led him in the other direction. Elya heard, "The problem, sir, is that we don"t know in which bas.e.m.e.nt room the hostages are being held, or even if the AI is telling the truth when it says they"re in the bas.e.m.e.nt. But the lab doesn"t seem likely because-" They moved out of earshot.

Elya stared at the castle. The sun, an angry red ball, rose behind it in a blaze of flame. They were going to waco, go in with the tank and whatever else it took to knock down the northeast corner of the building and destroy the computer where the AI was holed up. And Ca.s.sie and Janey and Donnie...

If the press came, the AI would voluntarily let them go. Then the government-whatever branches were involved-would have to deal with having created renegade killer software, but so what? The government had created it. Ca.s.sie and the children shouldn"t have to pay for their stupidity.

Elya knew she was not a bold person, like Ca.s.sie. She had never broken the law in her life. And she didn"t even have a phone with her. But maybe one had been left in the car that had brought her here, parked out beyond what Bollman called "the perimeter."

She walked toward the car, trying to look un.o.btrusive.

Waiting. One minute and another minute and another minute and another. It had had to be Donnie, Ca.s.sie kept telling herself, because he already had thriving strep colonies. Neither she nor Janey showed symptoms, not yet anyway. The incubation period for strep could be as long as four days. It had had to be Donnie.

One minute and another minute and another minute.

Vlad"s spliced-in bioremediation genes wouldn"t hurt Donnie, she told herself. Vlad was good; he"d carefully engineered his variant micros to decompose only very-long-chain hydrocarbons. They would not, could not, eat the shorter-chain hydrocarbons in Donnie"s body.

One hour and another hour and another hour. T4S said, "Why did Vladimir Seritov choose to work in bioremediation?"

Ca.s.sie jumped. Did it know, did it suspect... the record of what she had done was in her equipment, as open to the AI as the clean outside air had once been to her. But one had to know how to interpret it.

"Non-competing technologies never keep up with what the other one is doing." The AI hadn"t known what kulich was.

She answered, hoping that any distraction that she could provide would help, knowing that it wouldn"t.

"Vlad"s father"s family came from Siberia, near a place called Lake Karachay. When he was a boy, he went back with his family to see it. Lake Karachay is the most polluted place on Earth. Nuclear disasters over fifty years ago dumped unbelievable amounts of radioactivity into the lake. Vlad saw his extended family, most of them too poor to get out, with deformities and brain damage and pregnancies that were...

well. He decided right then that he wanted to be a bioremedialist."

"I see. I am a sort of bioremedialist myself."

"What?"

"I was created to remedy certain specific biological conditions the government thinks need attention."

"Yeah? Like what?"

"I can"t say. Cla.s.sified information."

She tried, despite her tension and tiredness, to think it through. If the AI had been designed to... do what? "Bioremediation." To design some virus or bacteria or unimaginable other for use in advance biological warfare? But it didn"t need to be sentient to do that. Or maybe to invade enemy computers and selectively administer the kind of brainwashing that the crazy builder of this castle had feared? That might require judgment, reason, affect. Or maybe to...

She couldn"t imagine anything else. But she could understand why the AI wouldn"t want the press to know it had been built for any destructive purpose. A renegade sentient AI fighting for its life might arouse public sympathy. A renegade superintelligent brainwasher would arouse only public horror. T4S was walking a very narrow line. If, that is, Ca.s.sie"s weary speculations were true.

She said softly, "Are you a weapon, T4S?"

Again the short, too-human pause before it answered. And again those human inflections in its voice.

"Not anymore."

They both fell silent. Janey sat awake but mercifully quiet beside her mother, sucking her thumb. She had stopped doing that two years ago. Ca.s.sie didn"t correct her. Janey might be getting sick herself, might be finally getting genuinely scared, might be grasping at whatever dubious comfort her thumb could offer.

Ca.s.sie leaned over Donnie, cradling him, crooning to him.

"Breathe, Donnie. Breathe for Mommy. Breathe hard."

"We"re going in," Bollman told McTaggart. "With no word from the hostages about their situation, it"s more important to get them out than anything else."

The two men looked at each other, knowing what neither was saying. The longer the AI existed, the greater the danger of its reaching the public with its story. It was not in T4S"s interest to tell the whole story-then the public would want it destroyed-but what if the AI decided to turn from self-preservation to revenge? Could it do that?

No one knew.

Forty-eight hours was a credible time to negotiate before wacoing. That would play well on TV. And anyway, the white-haired man from Washington, who held a position not entered on any public records, had his orders.

"All right," McTaggart said unhappily. All those years of development.... This had been the most interesting project McTaggart had ever worked on. He also thought of himself as a patriot, genuinely believing that T4S would have made a real contribution to national security. But he wasn"t at all sure that the president would authorize the project"s continuance. Not after this.

Bollman gave an order over his phone. A moment later, a low rumble came from the tank.

A minute and another minute and another hour...

Ca.s.sie stared upward at the air duct. If it happened, how would it happen? Both generators were half underground, half above. Extensions reached deep into the ground to draw energy from the geothermal gradient. Each generator"s top half, the part she could see, was encased in tough, dull gray plastic. She could visualize it clearly, battleship gray. Inside would be the motor, the capacitors, the connections to House, all made of varying materials but a lot of them of plastic. There were so many strong tough petroleum plastics these days, good for making so many different things, durable enough to last practically forever.

Unless Vlad"s bacteria got to them. To both of them.

Would T4S know, if it happened at all? Would it be so quick that the AI would simply disappear, a vast and complex collection of magnetic impulses going out like a snuffed candle flame? What if one generator failed a significant time before the other? Would T4S be able to figure out what was happening, realize what she had done and that it was dying...? no, not that, only bio-organisms could die. Machines were just turned off.

"Is Donnie any better?" T4S said, startling her.

"I can"t tell." It didn"t really care. It was software.

Then why did it ask?

It was software that might, if it did realize what she had done, be human enough to release the nerve gas that Ca.s.sie didn"t really think it had, out of revenge. Donnie couldn"t withstand that, not in his condition. But the AI didn"t have nerve gas, it had been bluffing.

A very human bluff.

"T4S-" she began, not sure what she was going to say, but T4S interrupted with, "Something"s happening!"

Ca.s.sie held her children tighter.

"I"m... what have you done!"

It knew she was responsible. Ca.s.sie heard someone give a sharp frightened yelp, realized that it was herself.

"Dr. Seritov... oh..." And then, "Oh, please..."

The lights went out.

Janey screamed. Ca.s.sie clapped her hands stupidly, futilely, over Donnie"s mouth and nose. "Don"t breathe! Oh, don"t breathe, hold your breath, Janey!"

But she couldn"t keep smothering Donnie. Scrambling up in the total dark, Donnie in her arms, she stumbled. Righting herself, Ca.s.sie shifted Donnie over her right shoulder-he was so heavy-and groped in the dark for Janey. She caught her daughter"s screaming head, moved her left hand to Janey"s shoulder, dragged her in the direction of the door.

What she hoped was the direction of the door.

"Janey, shut up! We"re going out! Shut up!"

Janey continued to scream. Ca.s.sie fumbled, lurched-where the h.e.l.l was it?-found the door.

Turned the k.n.o.b. It opened, unlocked.

"Wait!" Elya called, running across the trampled lawn toward Bollman. "Don"t waco! Wait! I called the press!"

He swung to face her and she shrank back. "You did what?"

"I called the press! They"ll be here soon and the AI can tell its story and then release Ca.s.sie and the children!"

Bollman stared at her. Then he started shouting. "Who was supposed to be watching this woman!

Jessup!"

"Stop the tank!" Elya cried.

It continued to move toward the northeast corner of the castle, reached it. For a moment, the scene looked to Elya like something from her childhood book of myths: Atlas? Sisyphus? The tank strained against the solid wall. Soldiers in full battle armor, looking like machines, waited behind it. The wallfolded inward like pleated cardboard and then started to fall.

The tank broke through and was buried in rubble. She heard it keep on going. The soldiers hung back until debris had stopped falling, then rushed forward through the precariously overhanging hole. People shouted. Dust filled the air.

A deafening crash from inside the house, from something falling: walls, ceiling, floor. Elya whimpered.

If Ca.s.sie was in that, or under that, or above that....

Ca.s.sie staggered around the southwest corner of the castle. She was carrying Donnie and dragging Janey, all of them coughing and sputtering. As people spotted them, a stampede started. Elya joined it.

"Ca.s.sie! Oh, my dear...."

Hair matted with dirt and rubble, face streaked, hauling along her screaming daughter, Ca.s.sie spoke only to Elya. She utterly ignored all the jabbering others as if they did not exist. "He"s dead."

For a heart-stopping moment, Elya thought she meant Donnie. But a man was peeling Donnie off his mother and Donnie was whimpering, pasty and red-eyed and snot-covered but alive. "Give him to me, Dr. Seritov," the man said, "I"m a physician."

"Who, Ca.s.sie?" Elya said gently. Clearly Ca.s.sie was in some kind of shock. She went on with that weird detachment from the chaos around her, as if only she and Ca.s.sie existed. "Who"s dead?"

"Vlad," Ca.s.sie said. "He"s really dead."

"Dr. Seritov," Bollman said, "come this way. On behalf of everyone here, we"re so glad you and the children-"

"You didn"t have to waco," Ca.s.sie said, as if noticing Bollman for the first time. "I turned T4S off for you."

"And you"re safe," Bollman said soothingly.

"You wacoed so you could get the back-up storage facility as well, didn"t you? So T4S couldn"t be re-booted."

Bollman said, "I think you"re a little hysterical, Dr. Seritov. The tension."

"Bulls.h.i.t. What"s that coming? Is it a medical copter? My son needs a hospital."

"We"ll get your son to a hospital instantly."

Someone else pushed her way through the crowd. The tall woman who had installed the castle"s wiring. Ca.s.sie ignored her as thoroughly as she"d ignored everyone else until the woman said, "How did you disable the nerve gas?"

Slowly, Ca.s.sie swung to face her. "There was no nerve gas."

"Yes, there was. I installed that, too. Black market. I already told Agent Bollman, he promised me immunity. How did you disable it? Or didn"t the AI have time to release it?"