"When was Badri's last course of antivirals?"

Finch took a considerable time looking through the sheaf of printouts, Scriptures and lavatory paper tallies. "Here it is, sir. September fourteenth."

"Did he have the full course?"

"Yes, sir. Receptor analogues, MPA booster, and seasonals."

"Has he ever had a reaction to an antiviral?"

"No, sir. There's nothing under Allergies in the history. I already told Dr. Ahrens that."

Badri had had all his antivirals. He had no history of reactions.

"Have you been to New College yet?" Dunworthy asked.

"No, sir, I'm just on my way. What should I do about supplies, sir? We've adequate stores of soap, but we're very low on lavatory paper."

The door opened, but it wasn't Mary. It was the medic who had been sent to fetch Montoya. He went over to the tea trolley and plugged in the electric kettle.

"Should I ration the toilet paper, do you think, sir," Finch said, "or put up notices asking everyone to conserve?"

"Whatever you think best," Dunworthy said and rang off.

It must still be raining. The medic's uniform was wet, and when the kettle boiled, he put his red hands over the steam, as if trying to warm them.

"Are you quite finished using the telephone?" Gilchrist said.

Dunworthy handed it to him. He wondered what the weather was like where Kivrin was, and whether Gilchrist had had Probability compute the chances of her coming through in the rain. Her cloak had not looked specially waterproof, and that friendly traveller who was supposed to come along within l.6 hours would have holed up in a hostelry or haymow till the roads dried enough to be passable.

Dunworthy had taught Kivrin how to make a fire, but she could hardly do so with wet kindling and numb hands. Winters in the 1300's had been cold. It might even be snowing. The Little Ice Age had just begun in 1320, the weather eventually getting so cold that the Thames froze over. The lower temps and erratic weather had played such havoc with the crops that some historians blamed the Black Death's horrors on the malnourished state of the peasants. The weather had certainly been bad. In the autumn of 1348, it had rained in one part of Oxfordshire every day from Michaelmas to Christmas. Kivrin was probably lying there on the wet road, half-dead from hypothermia.

And broken out in a rash, he thought, from her over-doting tutor worrying too much about her. Mary was right. He did sound like Mrs. Gaddson. The next thing he knew he'd be plunging off into 1320, forcing the doors of the net open like Mrs. Gaddson on the tube, and Kivrin would be as glad to see him as William was going to be to see his mother. And as in need of help.

Kivrin was the brightest and most resourceful student he had ever had. She surely knew enough to get in out of the rain. For all he knew, she had spent her last vac with the Eskimos, learning to build an igloo.

She had certainly thought of everything else, even down to her fingernails. When she had come in to show him her costume, she had held up her hands. Her nails had been broken off, and there were traces of dirt in the cuticles. "I know I'm supposed to be nobility, but rural nobility, and they did a lot of farm chores in between Bayeaux Tapestries, and East Riding ladies didn't have scissors till the 1600's, so I spent Sunday afternoon in Montoya's dig, grubbing among the dead bodies, to get this effect." There was obviously no reason to worry about a minor detail like snow.

But he couldn't help it. If he could speak to Badri, ask him what he'd meant when he said, "Something wrong," make certain the drop had gone properly and that there hadn't been too much slippage, he might be able to stop worrying. But Mary had not been able even to get Badri's NHS number till Finch phoned with it. He wondered if he were still unconscious. Or worse.

He got up and went over to the tea trolley and made himself a cup of tea. Gilchrist was on the phone again, apparently speaking to the porter. The porter didn't know where Basingame was either. When Dunworthy had talked to him, he had told him he thought Basingame had mentioned Loch Balkillan, a lake that turned out not to exist.

Dunworthy drank his tea. Gilchrist rang up the bursar and the deputy warden, neither of whom knew where Basingame had gone. The nurse who had guarded the door earlier came in and finished the blood tests. The male medic picked up one of the inspirational brochures and began to read it.

Montoya filled out her admissions form and her lists of contacts. "What am I supposed to do?" she asked Dunworthy. "Write down the people I've been in contact with today?"

"The past three days," he said.

They continued to wait. Dunworthy drank another cup of tea. Montoya rang up the NHS and tried to persuade them to give her a quarantine exemption so she could go back to the dig. The female medic went back to sleep.

The nurse wheeled in a trolley with supper on it. "'Greet chere made our hoste us everichon, And to the soper sette us anon,'" Latimer said, the only remark he had made all afternoon.

While they ate, Gilchrist regaled Latimer with his plans for sending Kivrin to the aftermath of the Black Death. "The accepted historical view is that it completely destroyed mediaeval society," he told Latimer as he cut his roast beef, "but my research indicates it was purgative rather than catastrophic."

From whose point of view? Dunworthy thought, wondering what was taking so long. He wondered if they were truly processing the blood tests or if they were simply waiting for one or all of them to collapse across the tea trolley so they could get a fix on the incubation period.

Gilchrist rang up New College again and asked for Basingame's secretary.

"She's not there," Dunworthy said. "She's in Devonshire with her daughter for Christmas."

Gilchrist ignored him. "Yes. I need to get a message through to her. I'm trying to reach Mr. Basingame. It's an emergency. We've just sent an historian to the 1300's, and Balliol failed to properly screen the tech who ran the net. As a result, he's contracted a contagious virus." He put the phone down. "If Mr. Chaudhuri failed to have any of the necessary antivirals, I'm holding you personally responsible, Mr. Dunworthy."

"He had the full course in September," Dunworthy said.

"Have you proof of that?" Gilchrist said.

"Did it come through?" the medic asked.

They all, even Latimer, turned to look at her in surprise. Until she'd spoken, she'd seemed fast asleep, her head far forward on her chest and her arms folded, holding the contacts lists.

"You said you sent somebody back to the Middle Ages," she said belligerently. "Did it?"

"I'm afraid I don't — " Gilchrist said.

"This virus," she said. "Could it have come through the time machine?"

Gilchrist looked nervously at Dunworthy. "That isn't possible, is it?"

"No," Dunworthy said. It was obvious Gilchrist knew nothing about the continuum paradoxes or string theory. The man had no business being Acting Head. He didn't even know how the net he had so blithely sent Kivrin through worked. "The virus couldn't have come through the net."

"Dr. Ahrens said the Indian was the only case," the medic said. "And you said," she pointed at Dunworthy, "that he'd had the full course. If he's had his antivirals, he couldn't catch a virus unless it was a disease from somewhere else. And the Middle Ages was full of diseases, wasn't it? Smallpox and the plague?"

Gilchrist said, "I'm certain that Mediaeval has taken steps to protect against that possibility — "

"There is no possibility of a virus coming through the net," Dunworthy said angrily. "The space-time continuum does not allow it to happen."

"You send people through," she persisted, "and a virus is smaller than a person."