Thora stood with her hands on her hips, looking as if she meant to stand in that spot all day if that was what it took to see Andrew Rusk. It struck Will then that for the first time he was seeing her dressed like a normal person. No designer outfit. No fancy hairdo. Just tight blue jeans and an even tighter white T-shirt. Thora was clearly giving the receptionist the hairy eyeball, but the blonde behind the desk was giving as good as she got. Without warning, Thora whirled and marched back toward the elevator.

"You going down, ma'am?" Will asked.

"You're damn right," Thora snapped.

As the elevator whooshed toward the lobby, Thora cursed steadily under her breath. In the closeness of the car, Will saw that her neck was blotchy with red spots, the way his wife looked when she was about to explode in a fit of temper. There were dark circles under both eyes. Will needed to talk to Alex in a hurry. Something had gone down last night, and they needed to know what it was.

When the elevator opened, Thora did not march out to the street. She walked aimlessly around the lobby like the survivor of a car crash. Will had seen a lot of desperate people during his years as a cop, and all his instincts told him this lady was about to snap.

He took out his cell phone and speed-dialed Alex. Her phone kicked him straight to voice mail. He jammed the phone back into his pocket and sat down on a padded bench. For five weeks, he had been helping his best friend's daughter, out of a bottomless sense of obligation. He had worked a lot of dead-end cases over the years, and about ten days ago he had decided this was one of them. But now adrenaline was flushing through his system the way it always did when a case started to break. For a brief moment, he thought of young Grace Morse, who would never see her son graduate high school. For an even briefer moment, he thought of the daughter he himself had lost all those years ago. When he got up to follow Thora out to the street, all the aches and pains of age were gone. He felt younger than he had in years. Wherever this crazy woman led him, Will would follow.

Alex was standing outside the hospital men's room when the elevator door opened and the bearded man with the birthmark that she'd met yesterday stepped out. He walked down the hall without glancing up, his eyes on a file in his hand. But then he turned, looked back at Alex, and said, "Hello, again."

"Hello," Alex called.

The bearded man smiled, then walked down the corridor and turned toward the academic offices. Alex hesitated, then followed. As she rounded the final corner, she saw his white-coated back disappear into an office. The brass plate on the door said ELDON TARVER, MD.

She hurried back to the men's room, but she saw no sign of Chris in the hall. She cracked open the bathroom door and called his name.

"What is it?" Chris groaned.

"I just saw Dr. Tarver. I was in the elevator with him yesterday and didn't even know it."

"Where is he now?"

"In his office. You almost done?"

"Yeah. Don't talk to him without me."

"Hurry, Chris."

She shut the door and went back down to Tarver's leg of the hall. His door was still closed. She was tempted to knock, but what excuse did she have to start a conversation? The only thing they shared was facial disfigurement. The guy would think she was coming on to him.

"Okay," Chris said, rounding the corner with a pale, clammy face.

"Can you make it?"

"I think so."

She turned to the door and knocked hard, but there was no answer. She waited, then knocked again. No response.

"He's gone?" she said. "That's weird."

"Why? I'm sure he just-"

"Oh, hello," said the now familiar bass voice. "What can I do for you?"

Chris held out his hand. "Dr. Tarver, I'm Chris Shepard, an internist from Natchez."

Dr. Tarver shook his hand. "Have you come to see me?"

"I suppose so. Pete Connolly recommended you as an expert on oncogenic viruses, and specifically retroviruses."

Tarver looked surprised. "I'm not sure I would put myself forward as that. I hold several degrees, but I'm not board-certified in virology."

"Nevertheless, both Pete and Dr. Pearson seem to think you're quite knowledgeable in the area."

"I do have quite a bit of practical experience." Dr. Tarver looked at Alex. "And you are…?"

"Nancy Jenner. I'm Dr. Shepard's chief nurse."

Dr. Tarver's eyes twinkled. He looked at Chris and said, "I envy you."

Chris cut his eyes at Alex, but she ignored him.

"Why don't we step into my office?" Tarver said, glancing at his watch. "I have about five minutes before I'm due somewhere."

He admitted them to an office much less spacious than the one occupied by Dr. Pearson. Bookshelves lined three of the four walls; the fourth was studded with framed photographs, many of them black-and-white. Tarver was older than she'd thought, Alex realized. There was a picture of him with President Richard Nixon; Nixon was pinning something on his chest. Another showed Tarver standing in front of a familiar-looking building with a long banner hanging over its entrance: FREE AIDS TESTING TODAY. In one picture Tarver was surrounded by emaciated black children, all reaching for him as though he were Albert Schweitzer. Alex studied the photos while Chris questioned the doctor.

"A cluster of cancers in Natchez, you say?" asked Tarver. "I wasn't aware of that. Natchez is in Adams County, correct?"

"Yes. Blood cancers, specifically," said Chris. "Several local doctors are starting to wonder if these cases might have a common etiology."

"A viral etiology?"

"Well, we don't know. I was thinking radiation exposure, but we can't pin down a common source. Most of the patients work at different places and live in different parts of town."

"Which militates against an environmental cause, as well," said Tarver.

"That's how I got onto the virus angle. I know that several cancers have been proved to have a viral etiology, or at least a viral mediator."

"That's more true in animals than humans. I can't think of a single case in which a virus has produced a cluster of cancers."

Chris looked surprised. "Surely there must be some cervical cancers like that, in urban areas with a high degree of sexual promiscuity?"

Tarver nodded in surprise. "I'm sure you're right. But those studies haven't been done. The process of viral oncogenesis is a long one. Decades long, in some cases. It's not like tracking a herpes epidemic. You could be in the midst of an HPV epidemic and not even know it. In fact, in some places I think we are. Sexual promiscuity is one of the best things that ever happened to the virus as an organism. In the Darwinian sense, I mean."

Alex was moving from photo to photo on the office wall. The birthmark made it easy to pick out Dr. Tarver, even in large group shots. Though it wasn't technically a birthmark, she remembered. It was something to do with malformed arteries and veins. As she studied the pictures, a fact she'd learned back at Quantico bubbled to the forefront of her mind. Many serial murderers suffered from some physical deformity that set them apart during their childhood. It was crazy to suspect Tarver, of course-a guy she had simply gotten onto an elevator with-and yet…he certainly had the sophisticated knowledge that their high-tech murders would require. And there was something about him, a quiet forcefulness and logical precision that made him seem capable of decisive, maybe even extreme, action; whereas Matt Pearson seemed more conventional.

Chris was speaking medical jargon now, an esoteric version far above her level. As his voice droned on, one photograph caught Alex's eye. In it, Dr. Tarver and a man wearing an army uniform stood on either side of a beautiful blond woman. Behind them stood a fortresslike building with a sign on its front that read VCP. The breast of Tarver's lab coat bore the same legend: VCP. Tarver was much younger in the photo, with a full head of hair and no beard. The military officer reminded Alex a little of her father. And the woman…she had that brainy look like the models in magazine ads for saturation language courses, the ones that made businessmen think they could get laid overseas if only they would learn a little French.