Fields laughed and backed off, and we waited another fifteen minutes for Leona to finish up.

"We'll bring the whole set down the hall to Simon Cranberg," Fields told us. "He'll let us know if the prints match whatever's on record for Darwin Bishop and Billy."

We were already headed out the door for that session when Leona called to us. "I think I should have dusted the inside of the bottle, too," she said.

We looked back at her.

"The suspect might have been careful not to touch the outer surface," she said, "but not as careful removing the pills."

"She's right," Fields said.

We walked back to the lab bench. Anderson surrendered the paper bag with the bottle inside.

Leona pulled it out, twisted off the cap, and squinted inside. "Hmm," she said.

"Hmm, what?" I asked.

She didn't answer, instead picking up a pair of tweezers and fishing inside the bottle with them. When she pulled them out, a two-inch photographic negative was caught in their pincer grip.

"What the hell is that?" Anderson said.

"It was curved flush to the inside wall," she said. "The color's so close to the orange plastic that we wouldn't have seen it if we didn't take our time and go the extra mile." She pointed a crooked finger at Fields. "Let that be a lesson to you." She held the negative up to the light so we could all get a peek at it. The image was small and shadowy, but it looked like a beach scene, with tiny people in the foreground.

"Let's get a print made," Fields said. "It won't take more than a couple minutes."

We left the bottle with Leona so she could lift any prints from the interior wall. Then we dropped the negative with the photography department and headed to Cranberg's office.

Simon Cranberg turned out to be a lumbering man in overalls, with lamb chop sideburns and half-glasses-a cross between Ben Franklin and Attila the Hun. He had already loaded Darwin Bishop's prints onto his computer, so we started by looking for their match on Leona's pieces of tape. Cranberg scanned each length with a magnifying glass, checking his computer screen now and then. Within a minute he decided to run one of the strips through a scanner that transferred the lifted prints to a split screen next to the ones from Bishop's criminal record. "That's a match," he said with certainty. "Darwin Bishop's prints are on that bottle."

That was no surprise to me. I glanced at Anderson, expecting him to look reassured, but he looked oddly unsettled. "What's wrong?" I said.

"Nothing," he answered unconvincingly. "It's going like we thought it would."

"Let's look at the boy," Fields said.

Cranberg went over each length of tape meticulously, loading every image onto the screen next to Billy's fingerprints from Immigration. A few times he went back to pieces of tape he had already looked at. After he had scanned the last of them, he shook his head. "None of the lifted prints belongs to Billy Bishop," he said.

"You're certain," I said.

"A bunch of people barehanded that medicine bottle," Cranberg said. "Billy definitely isn't one of them."

"That's it, then," Fields said. "You've got your answer. I can tell you, it isn't the one Captain O'Donnell will want to hear."

I felt a real sense of relief for the first time since taking the Bishop case. Because I believed what Anderson had said: If Billy had tried to kill Tess, he wouldn't leave prints everywhere except the prescription bottle, not to mention leaving a note. And if Billy hadn't poisoned Tess, it was highly unlikely he had killed Brooke. I hoped a jury would see it that way, too.

I looked over at Anderson again, expecting a mirror image of my mood. He winked and nodded his head tentatively. No sign of triumph anywhere. Maybe, I told myself, he had simply run out of steam getting us where we needed to go.

A young man from the photography department appeared at the door, holding a manila envelope.

"Perfect timing," Fields said. "Let's get a look at that photograph. Maybe we're on a roll here."

"Did you want to review it first?" the young man asked Fields. He sounded like he was making a suggestion.

Fields either didn't pick up on his discomfort or he ignored it. "No need," he said. "We're all friends here." He took the envelope, opened it, and pulled out a five-by-eight black-and-white glossy. Then he stood there staring at it, his face losing its permanent smile for the first time since I had met him. "What's this about?" he said quietly.

I walked over and looked at the photograph. My heart fell. The muscles in my back felt like they were knotting themselves into a noose around my gut. I looked at Anderson, who had hung his head. No doubt he had recognized the beach scene even when Leona had held up the negative. Because he and Julia were the only two figures in it, holding each other close on a deserted stretch of Nantucket beach. Before I could think what to say to him, he walked past Fields and me, and out of the room.

I followed Anderson, concentrating to keep my legs moving. Waves of emotion were crashing inside me. I felt betrayed, enraged, and foolish, all at the same time. I also felt unnerved. I was lost in the geography of the Bishop case. If North had lied to me about his connection with Julia, what else had he lied about? Could I rely on any of the data he had fed me about Bishop? He was the one, after all, who had told me about Bishop's affair with Claire Buckley. He was the one who had confirmed Bishop's having taken out life insurance on the twins.

My mind upped the ante. Could Anderson, I wondered, have been directing my seduction from the beginning? Might he and Julia be partners in crime, using me to help focus suspicion on Darwin Bishop, to get him out of their way?

And what about my having been attacked outside Mass General? Anderson knew my itinerary better than anyone. Was it possible I was winning over a woman he wanted badly enough to have me killed? Was the letter Julia had written meant for him?

I couldn't believe I needed to do it, but I checked for the Browning Baby in my pocket as I headed down the hallway toward the exit to the heliport.

I didn't get there. As I passed an open door to my right, a few feet from the exit, Anderson called my name. I stopped and looked into what seemed to be an anatomy lab, full of gleaming, stainless-steel dissection tables. Anderson was seated on one of them. I walked cautiously inside.

Anderson stared up at the ceiling, shook his head, then looked at me. "I'd explain, but I can't," he said. "It was just something that happened. I never would have…"

"I didn't want this fucking case!" I seethed. "I didn't need this case! Do you understand? You dragged me into it." My stitches pulled viciously at my insides. I closed my eyes and tried to catch my breath as the pain died down slowly. I looked back at Anderson. "Why the hell didn't you tell me about this?"

"I tried, in my own way," he said. "I kept warning you to keep your distance."

"That's not the same as telling me you were with her," I said.

"I was never with her," Anderson said, holding up his hands. "We were headed there-maybe. I can't even say that was in the cards." He dropped his hands to his thighs. "Let me try to tell you exactly what happened."

I stared at him.

"I met her about a month after I took the job down here. That's going back about a year and a half. She and Darwin hosted a fund-raiser for the Pine Street Inn, the big shelter in Boston. All the heavy hitters around here turned out, including all the local politicians. I was new in town, so I spoke to the crowd for ten, fifteen minutes about my plans for policing the island. She called me up, maybe three weeks later, said she wanted to talk about trying to help some of the kids on the island who were struggling with drug problems-maybe start some kind of community action group."