But my grandfather had enlarged it, then enlarged it again, and again, and again, each enlargement placed behind the preceding picture. And from the page a face grew, bigger and bigger until it took on the size and dimensions of a skull, the ink turning the eyes into dark pits, the face a construct of tiny black and white dots. The man in the picture had become a specter, his features indistinguishable, unrecognizable to anyone except my grandfather. For my grandfather had sat beside him in that bar, had smelled him, had listened as this man directed him to a tree where dead girls twisted in the breeze.

This, my grandfather believed, was Caleb Kyle.

At the airport, I called the psychology department at Harvard, gave them my ID number and asked them if Rachel Wolfe was due to teach that day. I was informed that Ms. Wolfe was due to give a tutorial to psychology students at 6 P.M. It was now 5:15 P.M. If I missed Rachel on campus, or if she canceled her tutorial, there were people who could get a residential address for me but it would take time, and time, I was rapidly coming to realize, was something I just didn't have. I climbed into a cab and my fingers beat an impatient tattoo on the window all the way to Harvard Square. A UC election banner hung outside the Grafton pub and a lot of the kids on the streets wore student election badges on their bags and coats as I headed across the campus to the junction of Quincy and Kirkland. I sat in the shadow of the Church of the New Jerusalem, across from the William James Hall, and waited.

At 5:55 P.M. a figure dressed in a black wool overcoat, anklelength boots and black trousers, her red hair tied back with a black and white ribbon, walked down Quincy and entered the James Hall. Even at a distance, Rachel still looked beautiful and I caught one or two male students sneaking looks at her as she passed. I kept a short distance behind her as I followed her into the entrance hall and watched her take the stairs to seminar room 6 on the lower ground floor, just to make sure that she wasn't going to cancel and leave. I followed her as she entered the seminar room and closed the door, then I took a seat in a plastic chair with a view of the door and waited.

After an hour, the tutorial ended and students began to stream out, notebooks clutched to their chests or poking out of their bags. I moved aside to let the last student leave, then stepped into a small classroom dominated by a single big table, with chairs arranged around it and against the walls. At the head of the table, beneath a blackboard, sat Rachel Wolfe. She was dressed in a dark green sweater with a man's white shirt beneath it, the collar turned up around her neck. As always, she wore some light makeup, carefully applied, and a dark red lipstick.

She looked up expectantly, a half-smile on her face that froze as soon as she saw me. I closed the door gently behind me and took the first vacant seat at the table, which was just about as far away from her as I could get.

"Hi," I said.

She didn't speak for a moment before very deliberately putting her pens and notes away in a leather attaché case. Then she stood and started to shrug on her coat. "I asked that you not try to contact me," she said, as she struggled to find her left sleeve. I stood and walked over to her, and held the sleeve out so she could get her arm in. I felt kind of sleazy intruding on her space that way, but I also felt a momentary twinge of resentment: Rachel had not been the only one hurt in Louisiana in the hunt for the Traveling Man. The resentment quickly passed, to be replaced by guilt as I recalled the feel of her in my arms, her body racked by sobs after she was forced to kill a man in the Metairie cemetery. Once again, I saw her raising the gun, her finger tightening on the trigger, fire leaping from the muzzle as the gun bucked in her hands. Some deep, unquenchable instinct for survival had kicked in on that awful summer day, fueling her actions. I think that now, when she looked at me, she recalled what she had done, and she felt a fear of what I represented: that capacity for violence that had briefly exploded into existence within her and whose embers still glowed redly in her dark places.

"Don't worry," I said, lying a little. "I'm here for professional reasons, not personal ones."

"Then I certainly don't want to hear about it." She turned, her case beneath her arm. "Excuse me, I have work to do."

I put out a hand to touch her arm, and she glared at me. I withdrew it. "Rachel, please. I need your help."

"Please, let me leave. You're blocking my way."

I moved back and she shuffled past me, her head down. She had the door open when I spoke again. "Rachel, listen to me, just for a moment. If not for me, then for Walter Cole."

She stopped at the door, but didn't turn around. "What about Walter?"

"His daughter Ellen is missing. I'm not sure, but it may have something to do with a case I'm working on. It may also be connected somehow to Thani Pho, the student who was killed last week."

Rachel paused, then took a deep breath, closed the door and sat down in the seat I had previously occupied. Just to keep things equal, I sat down in her seat.

"You have two minutes," she said.

"I need you to read a file, and give me an opinion on it."

"I don't do that anymore."

"I hear you're working on a study about the connection between violent crime and brain disorders, something involving brain scans."

I knew a little more than that. Rachel was involved in research into dysfunctions in two areas of the brain, the amygdala and the frontal lobe. As I understood it from reading a copy of an article she had contributed to a psychology journal, the amygdala, a tiny area of tissue in the unconscious brain, generates feelings of alarm and emotion, allowing us to respond to the distress of others. The frontal lobe is where emotions are registered, where self-consciousness emerges and plans are constructed. It is also the part of the brain that controls our impulses.

In psychopaths, it was now believed, the frontal lobe failed to respond when confronted with an emotional situation, possibly due to a failure in the amygdala itself or in the processes used to send its signals to the cortex. Rachel, and others like her, were pressing for a huge brain-scan survey on convicted criminals, arguing that they could reveal a connection between brain damage and psychopathic criminal behavior.

She frowned. "You seem to know a lot. I'm not sure that I like the idea of you keeping tabs on me."

I felt that twinge of resentment again. I felt it so strongly that my mouth twitched involuntarily. "It's not like that, but I see your ego is still strong and healthy."

Rachel smiled slightly, a tiny, fleeting thing. "The rest of me isn't quite so robust. I'm going to be scarred for life. I'm in therapy twice weekly and I've had to give up my own practice. I still think of you, and you still frighten me. Sometimes."

"I'm sorry." Maybe it was my imagination, but there was something in that pause, in that sometimes, that implied she thought of me in other ways too.

"I know. Tell me about this file."

And I did, giving her a brief run through the history of the killings, adding some of what Mrs. Schneider had told me and some of what I suspected, or had guessed, myself. "Most of it is in here." I raised the battered manila folder. "I'd like you to take a look, see what you can come up with."

She reached out and I slid the file to her across the long table. She flicked quickly through the handwritten notes, the carbon copies, the photographs. One of them was a crime scene photo taken by the banks of the Little Wilson. "Oh my God," she whispered, and closed her eyes. When she opened them again, there was a new light in them, the spark of professional curiosity but also something else, something that had attracted me to her in the first place.