Sitting beside Stanley, she was absurdly reminded of going to the movies with a boyfriend at the age of fourteen, and allowing him to put his hand up her sweater. The memory embarrassed her, and she felt her neck redden. She hoped Stanley would not notice.

On the monitor, she showed him Michael arriving at the main gate and presenting his pass. "The date and time are on the bottom of the screen," she said. It was fourteen twenty-seven on the eighth of December. She tapped the keyboard, and the screen showed a green Volkswagen Golf pulling into a parking space. A slight man got out and took a duffel bag from the back of the car. "Watch that bag," Toni said.

"Why?"

"There's a rabbit in it."

"How did he manage that?"

"I guess it's tranquilized, and probably wrapped up tightly. Remember, he's been dealing with laboratory animals for years. He knows how to keep them calm."

The next shot showed Michael presenting his pass again at reception. A pretty Pakistani woman of about forty came into the Great Hall. " That's Monica Ansari," said Stanley.

"She was his buddy. She needed to do some work on tissue cultures, and he was performing the routine weekend check on the animals."

They walked along the corridor Toni and Stanley had taken, but went past the turning for the control room and continued to the door at the end. It looked like all the other doors in the building, with four recessed panels and a brass knob, but it was made of steel. On the wall beside the door was the yellow-and-black warning of the international biohazard symbol.

Dr. Ansari waved a plastic pass in front of a remote card reader, then pressed the forefinger of her left hand to a small screen. There was a pause, while the computer checked that her fingerprint matched the information on the microchip embedded in the smart card. This ensured that lost or stolen cards could not be used by unauthorized persons. While Dr. Ansari waited, she glanced up at the television camera and gave a mock salute. Then the door opened and she stepped through. Michael followed.

Another camera showed them in a small lobby. A row of dials on the wall monitored the air pressure in the lab. The farther you went inside BSL4, the lower the air pressure. This downward gradient ensured that any leakage of air was inward, not outward. From the lobby they went to separate men's and women's changing rooms. "This is when he took the rabbit out of the bag," Toni said. "If his buddy that day had been a man, the plan wouldn't have worked. But he had Monica and, of course, there are no cameras in the changing rooms."

"But damn it, you can't put security cameras in changing rooms," Stanley said. "No one would work here."

"Absolutely," said Toni. "We'll have to think of something else. Watch this."

The next shot came from a camera inside the lab. It showed conventional rabbit racks housed in a clear plastic isolation cover. Toni froze the picture. "Could you explain to me what the scientists are doing in this lab, exactly?"

"Of course. Our new drug is effective against many viruses, but not all. In this experiment it was being tested against Madoba- 2, a variant of the Ebola virus that causes a lethal hemorrhagic fever in both rabbits and humans. Two groups of rabbits were challenged with the virus."

"Challenged?"

"Sorry-it's the word we use. It means they were infected. Then one group was injected with the drug."

"What did you find?"

"The drug doesn't defeat Madoba- 2 in rabbits. We're a bit disappointed. Almost certainly, it won't cure this type of virus in humans either."

"But you didn't know that sixteen days ago."

"Correct."

"In that case, I think I understand what Michael was trying to do." She touched the keyboard to unfreeze the picture. A figure stepped into shot wearing a light blue plastic space suit with a clear helmet. He stopped by the door to push his feet into rubber overboots. Then he reached up and grabbed a curly yellow air hose hanging from the ceiling. He connected it to an inlet on his belt. As air was pumped in, the suit inflated, until he looked like the Michelin Man.

"This is Michael," Toni said. "He changed faster than Monica, so at the moment he's in there alone."

"It shouldn't happen, but it does," Stanley said. "The two-person rule is observed, but not minute by minute. Merda." Stanley often cursed in Italian, having learned a ripe vocabulary from his wife. Toni, who spoke Spanish, usually understood.

On screen Michael went up to the rabbit rack, moving with deliberate slowness in the awkward costume. His back was to the camera and, for a few moments, the pumped-up suit shielded what he was doing. Then he stepped away and dropped something on a stainless-steel laboratory bench.

"Notice anything?" Toni said.

"No.

"Nor did the security guards who were watching the monitors." Toni was defending her staff. If Stanley had not seen what happened, he could hardly blame the guards for missing it, too. "But look again." She went back a couple of minutes and froze the frame as Michael stepped into shot. "One rabbit in that top right-hand cage."

"I see."

"Look harder at Michael. He's got something under his arm."

"Yes-wrapped in blue plastic suit fabric."

She ran the footage forward, stopping again as Michael moved away from the rabbit rack. "How many rabbits in the top right-hand cage?"

"Two, damn it." Stanley looked perplexed. "I thought your theory was that Michael took a rabbit out of the lab. You've shown him bringing one in!"

"A substitute. Otherwise the scientists would have noticed one was missing."

"Then what's his motivation? In order to save one rabbit, he has to condemn another to death!"

"Insofar as he was rational at all, I imagine he felt there was something special about the rabbit he saved."

"For God's sake, one rabbit is the same as another."

"Not to Michael, I suspect."

Stanley nodded. "You're right. Who knows how his mind was working at this point."

Toni ran the video footage forward. "He did his chores as usual, checking the food and water in the cages, making sure the animals were still alive, ticking off his tasks on a checklist. Monica came in, but she went to a side laboratory to work on her tissue cultures, so she could not see him. He went next door, to the larger lab, to take care of the macaque monkeys. Then he came back. Now watch."

Michael disconnected his air hose, as was normal when moving from one room to another within the lab-the suit contained three or four minutes' worth of fresh air, and when it began to run out the faceplate would fog, warning the wearer. He stepped into a small room containing the vault, a locked refrigerator used for storing live samples of viruses. Being the most secure location in the entire building, it also held all stocks of the priceless antiviral drug. He tapped a combination of digits on its keypad. A security camera inside the refrigerator showed him selecting two doses of the drug, already measured and loaded into disposable syringes.

"The small dose for the rabbit and the large one, presumably, for himself," Toni said. "Like you, he expected the drug to work against Madoba-2. He planned to cure the rabbit and immunize himself."

"The guards could have seen him taking the drug from the vault."

"But they wouldn't find that suspicious. He's authorized to handle these materials."

"They might have noticed that he didn't write anything in the log."

"They might have, but remember that one guard is watching thirty-seven screens, and he's not trained in laboratory practice."

Stanley grunted.

Toni said, "Michael must have figured that the discrepancy wouldn't be noticed until the annual audit, and even then it would be put down to clerical error. He didn't know I was planning a spot check."