"I'm afraid that's impossible," Gilchrist said hollowly. "I've been conducting research into the incidence of influenza in the 1300's. There are clear indications that a series of influenza epidemics in the first half of the fourteenth century severely weakened the populace, thereby lowering their resistance to the Black Death."

He picked up an ancient-looking book. I have found six separate references to outbreaks between October of 1318 and February of 1321." He held up a book and began to read. "'After the harvest there came upon all of Dorset a fever so fierce as to leave many dead. This fever began with an aching in the head and confusion in all the parts. The doctors bled them, but many died in despite.'"

A fever. In an age of fevers — typhoid and cholera and measles, all of them producing "aching of the head and confusion in all the parts."

"1319. The Bath Assizes for the previous year were cancelled," Gilchrist said, holding up another book. "'A malady of the chest that fell upon the court so that none, nor judge nor jury, were left to hear the cases,'" Gilchrist said. He looked at Dunworthy over the mask. "You stated that the public's fears over the net were hysterical and unfounded. It would seem, however, that they are based in solid historical fact."

Solid historical fact. References to fevers and maladies of the chest that could be anything, blood poisoning or typhus or any of a hundred nameless infections. All of which was beside the point.

"The virus cannot have come through the net," he said. "Drops have been made to the Pandemic, to World War I battles in which mustard gas was used, to Tel Aviv. Twentieth Century sent detection equipment to the site of St. Paul's two days after the pinpoint was dropped. Nothing comes through."

"So you say." He held up a printout. "Probability indicates a .003 per cent possibility of a microorganism being transmitted through the net and a 22.1 per cent chance of a viable myxovirus being within the critical area when the net was opened."

"Where in God's name do you get these figures?" Dunworthy said. "Pull them out of a hat? According to Probability," he said, putting a nasty emphasis on the word, "there was only a .04 per cent chance of anyone's being present when Kivrin went through, a possibility you considered statistically insignificant."

"Viruses are exceptionally sturdy organisms," Gilchrist said. "They have been known to lie dormant for long periods of time, exposed to extremes of temperature and humidity, and still be viable. Under certain conditions they form crystals which retain their structure indefinitely. When put back into solution they become infective again. Viable tobacco mosaic crystals have been found dating from the sixteenth century.

"There is clearly a significant risk of the virus's penetrating the net if opened, and under the circumstances I cannot possibly allow the net to be opened."

"The virus cannot have come through the net," Dunworthy said.

"Then why are you so anxious to have the fix read?"

"Because — " Dunworthy said, and stopped to get control of himself. "Because reading the fix will tell us whether the drop went as planned or whether something went wrong."

"Oh, you'll admit there's a possibility of error then?" Gilchrist said. "Then why not an error that would allow a virus through the net? As long as that possibility exists, the laboratory will remain locked. I'm certain Mr. Basingame will approve of the course of action I've taken."

Basingame, Dunworthy thought, that's what this is all about. It has nothing to do with the virus or the protesters or 'maladies of the chest' in 1318. This is all to justify himself to Basingame.

Gilchrist was Acting Head in Basingame's absence, and he had rushed through the reranking, rushed through a drop, intending no doubt to present Basingame with a brilliant fait accompli. But he hadn't got it. Instead, he'd got an epidemic and a lost historian and people picketing the college, and now all he cared about was vindicating his actions, saving himself even though it meant sacrificing Kivrin.

"What about Kivrin? Does Kivrin approve of your course of action?" he said.

"Ms. Engle was fully aware of the risks when she volunteered to go to 1320," Gilchrist said.

"Was she aware you intended to abandon her?"

"This conversation is over, Mr. Dunworthy." Gilchrist stood up. "I will open the laboratory when the virus has been sourced, and it has been proven to my satisfaction that there is no chance it came through the net."

He showed Dunworthy to the door. The porter was waiting outside.

"I have no intention of allowing you to abandon Kivrin," Dunworthy said.

Gilchrist crimped his lips under the mask. "And I have no intention of allowing you to endanger the health of this community." He turned to the porter. "Escort Mr. Dunworthy to the gate. If he attempts to enter Brasenose again, telephone the police." He slammed the door.

The porter walked Dunworthy across the quad, watching him warily, as if he thought he might turn suddenly dangerous.

I might, Dunworthy thought. "I want to use your telephone," he said when they reached the gate. "University business."

The porter looked nervous, but he set a telephone on the counter and watched while Dunworthy punched Balliol's number. When Finch answered, he said, "We've got to locate Basingame. It's an emergency. Phone the Scottish Fishing License Bureau and compile a list of hotels and inns. And get me Polly Wilson's number."

He wrote down the number, rang off, and started to punch it in and then thought better of it and telephoned Mary.

"I want to help source the virus," he said.

"Gilchrist wouldn't open the net," she said.

"No," he said. "What can I do to help with the sourcing?"

"What you were doing before with the primaries. Trace the contacts, look for the things I told you about, exposure to radiation, proximity to birds or livestock, religious that forbid antivirals. You'll need the contacts charts."

"I'll send Colin for them," he said.

"I'll have someone get them ready. You'd better check Badri's contacts back four to six days, as well, in case the virus did originate with him. The time of incubation from a reservoir can be longer than a person-to-person incubation period."

"I'll put William on it," he said. He pushed the phone back at the porter, who immediately came around the counter and walked him out to the pavement. Dunworthy was surprised he didn't follow him all the way to Balliol.

As soon as he got there, he phoned Polly Wilson. "Is there some way you can get into the net's console without having access to the laboratory?" he asked her. "Can you go in directly through the University's computer?"

"I don't know," she said. "The University's computer is moated. I might be able to rig a bettering ram, or worm in from Balliol's console. I'll have to see what the safeties are. Do you have a tech to read it if I can get it set up?"

"I'm getting one," he said. He rang off.

Colin came in, dripping wet, to get another roll of tape. "Did you know the sequencing came, and the virus is a mutant?"

"Yes," Dunworthy said. "I want you to go to Infirmary and get the contacts charts from your great-aunt."

Colin set down his load of placards. The one on top read, "Do Not Have a Relapse."

"They're saying it's some sort of biological weapon," Colin said. "They're saying it escaped from a laboratory."

Not Gilchrist's, he thought bitterly. "Do you know where William Gaddson is?"

"No." Colin made a face. "He's probably on the staircase kissing someone."

He was in the buttery, embracing one of the detainees. Dunworthy told him to find out Badri's whereabouts for Thursday through Sunday morning and to obtain a copy of Basingame's credit records for December, and went back to his rooms to telephone techs.