McAlpine grunted. As lab director he was responsible for the log, and the real reason for his mood was that he should have discovered the discrepancy himself. Toni's efficiency made him look bad.

She turned to the other man, who was the director of human resources. "How far down your list are we, James?"

James Elliot looked up from his computer screen. He dressed like a stockbroker, in a pin-striped suit and spotted tie, as if to distinguish himself from the tweedy scientists. He seemed to regard the safety rules as tiresome bureaucracy, perhaps because he never worked hands-on with viruses. Toni found him pompous and silly. "We've spoken to all but one of the twenty-seven staff that have access to BSL4," he said. He spoke with exaggerated precision, like a tired teacher explaining something to the dullest pupil in the class. "All of them told the truth about when they last entered the lab and opened the vault. None has noticed a colleague behaving strangely. And no one has a fever."

"Who's the missing one?"

"Michael Ross, a lab technician."

"I know Michael," Toni said. He was a shy, clever man about ten years younger than Toni. "In fact I've been to his home. He lives in a cottage about fifteen miles from here."

"He's worked for the company for eight years without a blemish on his record."

McAlpine ran his finger down a printout and said, "He last entered the lab three Sundays ago, for a routine check on the animals."

"What's he been doing since?"

"Holiday."

"For how long-three weeks?"

Elliot put in, "He was due back today." He looked at his watch. "Yesterday, I should say. Monday morning. But he didn't show up."

"Did he call in sick?"

"No."

Toni raised her eyebrows. "And we can't reach him?"

"No answer from his home phone or his mobile."

"Doesn't that strike you as odd?"

"That a single young man should extend his vacation without forewarning his employer? About as odd as rain in Glen Coe."

Toni turned back to McAlpine. "But you say Michael has a good record."

The lab director looked worried. "He's very conscientious. It's surprising that he should take unauthorized leave."

Toni asked, "Who was with Michael when he last entered the lab?" She knew he must have been accompanied, for there was a two-person rule in BSL4: because of the danger, no one could work there alone.

McAlpine consulted his list. "Dr. Ansari, a biochemist."

"I don't think I know him."

"Her. It's a woman. Monica."

Toni picked up the phone. "What's her number?"

Monica Ansari spoke with an Edinburgh accent and sounded as if she had been fast asleep. "Howard McAlpine called me earlier, you know."

"I'm sorry to trouble you again."

"Has something happened?"

"It's about Michael Ross. We can't track him down. I believe you were in BSL4 with him two weeks ago last Sunday."

"Yes. Just a minute, let me put the light on." There was a pause. "God, is that the time?"

Toni pressed on. "Michael went on holiday the next day."

"He told me he was going to see his mother in Devon."

That rang a bell. Toni recalled the reason she had gone to Michael Ross's house. About six months ago she had mentioned, in a casual conversation in the canteen, how much she liked Rembrandt's pictures of old women, with every crease and wrinkle lovingly detailed. You could tell, she had said, how much Rembrandt must have loved his mother. Michael had lit up with enthusiasm and revealed that he had copies of several Rembrandt etchings, cut out of magazines and auction house catalogues. She went home with him after work to see the pictures, all of old women, tastefully framed and covering one wall of his small living room. She worried that he was going to ask her for a date-she liked him, but not that way-but, to her relief, he genuinely wanted only to show off his collection. He was, she had concluded, a mother's boy.

"That's helpful," Toni said to Monica. "Just hold on." She turned to James Elliot. "Do we have his mother's contact details on file?"

Elliot moved his mouse and clicked. "She's listed as next of kin." He picked up the phone.

Toni spoke to Monica again. "Did Michael seem his normal self that afternoon?"

"Totally."

"Did you enter BSL4 together?"

"Yes. Then we went to separate changing rooms, of course."

"When you entered the lab itself, was he already there?"

"Yes, he changed quicker than I did."

"Did you work alongside him?"

"No. I was in a side lab, dealing with tissue cultures. He was checking on the animals."

"Did you leave together?"

"He went a few minutes before I did."

"It sounds to me as if he could have accessed the vault without your knowing about it."

"Easily."

"What's your impression of Michael?"

"He's all right… inoffensive, I suppose."

"Yeah, that's a good word for him. Do you know if he has a girlfriend?"

"I don't think so."

"Do you find him attractive?"

"Nice-looking, but not sexy."

Toni smiled. "Exactly. Anything odd about him, in your experience?"

"No."

Toni sensed a hesitation, and remained silent, giving the other woman time. Beside her, Elliot was speaking to someone, asking for Michael Ross or his mother.

After a moment, Monica said, "I mean, the fact that someone lives alone doesn't make them a nutcase, does it?"

Beside Toni, Elliot was saying into the phone, "How very strange. I'm sorry to have troubled you so late at night."

Toni's curiosity was piqued by what she could heat of Elliot's conversation. She ended her call, saying, "Thanks again, Monica. I hope you get back to sleep all right."

"My husband's a family doctor," she said. "We're used to phone calls in the middle of the night."

Toni hung up. "Michael Ross had plenty of time to open the vault," she said. "And he lives alone." She looked at Elliot. "Did you reach his mother's house?"

"It's an old folks' home," Elliot said. He looked frightened. "And Mrs. Ross died last winter."

"Oh, shit," said Toni.

POWERFUL security lights lit up the towers and gables of the Kremlin. The temperature was five below zero, but the sky was clear and there was no snow. The building faced a Victorian garden, with mature trees and shrubs. A three-quarter moon shed a gray light on naked nymphs sporting in dry fountains while stone dragons stood guard.

The silence was shattered by the roar of engines as two vans drove out of the garage. Both were marked with the international biohazard symbol, four broken black circles on a vivid yellow background. The guard at the gatehouse had the barrier up already. They drove out and turned south, going dangerously fast.

Toni Gallo was at the wheel of the lead vehicle, driving as if it were her Porsche, using the full width of the road, racing the engine, powering through bends. She feared she was too late. In the van with Toni were three men trained in decontamination. The second vehicle was a mobile isolation unit with a paramedic at the wheel and a doctor, Ruth Solomons, in the passenger seat.

Toni was afraid she might be wrong, but terrified she might be right.

She had activated a red alert on the basis of nothing but suspicion. The drug might have been used legitimately by a scientist who just forgot to make the appropriate entry in the log, as Howard McAlpine believed. Michael Ross might simply have extended his holiday without permission, and the story about his mother might have been no more than a misunderstanding. In that case, someone was sure to say that Toni had overreacted-like a typical hysterical woman, James Elliot would add. She might find Michael Ross safely asleep in bed with his phone turned off, and she winced to think what she would then say to her boss, Stanley Oxenford, in the morning.