"Don't know the word," Sam said wearily, reaching for his glass. "But I get the idea. You're saying I should leave it."

"I don't know what you should do," I said. A wave of fatigue and nausea enveloped me. God, I thought, what a week. "I'm probably the last person to ask. I just don't see the point of making a martyr of yourself and ditching your home and your career when it won't do anyone any good. You didn't do anything wrong. Right?"

Sam looked up at me. "Right," he said softly, bitterly. "I did nothing wrong."

Cassie wasn't the only one who was losing weight. It had been well over a week since I had eaten an actual meal, with food groups and everything, and I had been vaguely aware that when I was shaving I had to maneuver the razor into new little hollows around my jawline; but it wasn't until I was taking off my suit that night that I realized it was hanging off my hipbones and sagging away from my shoulders. Most detectives either lose or gain some weight during a big investigation-Sam and O'Gorman were both starting to look a little bulky around the middle from too much snatched junk food-and I'm tall enough that this is seldom noticeable, but if this case went on for much longer, I was going to have to buy new suits or go around looking like Charlie Chaplin.

This is what not even Cassie knows: the year I was twelve, I was a big kid. Not one of those featureless spherical children you see waddling down the street on preachy news segments about the moral inferiority of modern youth; in photos I just look sturdy, a little chunky maybe, tall for my age and horribly uncomfortable, but I felt monstrous and lost: my own body had betrayed me. I had shot up and out until it was unrecognizable to me, some hideous practical joke I had to carry around every moment of every day. It didn't help that Peter and Jamie looked exactly like they always had: longer in the leg, all their baby teeth gone, but still slight and light and invincible as ever.

It didn't last long, my chunky stage: the food at boarding school was, in keeping with literary tradition, so awful that even a kid who wasn't shaken and homesick and growing fast would have had a hard time eating enough of it to gain weight. And I hardly ate anything at all, that first year. At first the housemaster made me stay at the table on my own, for hours sometimes, until I forced down a few bites and his point, whatever it was, had been made; after a while I grew expert at slipping food into a plastic bag in my pocket, to be flushed away later. Fasting is, I think, a profoundly instinctive form of appeal. I'm sure I believed, in some inarticulate way, that if I ate little enough for long enough Peter and Jamie would be given back and everything would return to normal. By the beginning of my second year I was tall and thin with too many elbows, the way thirteen-year-olds are supposed to be.

I'm not sure why this, out of all the possibilities, should be my most closely guarded secret. I think the truth is this: I have always wondered whether this was the reason I was left behind, that day in the wood. Because I was fat; because I couldn't run fast enough; because, newly heavy and awkward, my balance shattered, I was afraid to jump off the castle wall. Sometimes I think about the sly, flickering line that separates being spared from being rejected. Sometimes I think of the ancient gods who demanded that their sacrifices be fearless and without blemish, and I wonder whether, whoever or whatever took Peter and Jamie away, it decided I wasn't good enough.

That Tuesday, first thing in the morning, I finally took the bus out to Knocknaree to pick up my car. Given the choice, I would have preferred never to think about Knocknaree again in my life, but I was sick of getting to and from work on jam-packed, sweat-smelling DARTs, and I needed to do a serious supermarket run soon, before Heather's head imploded.

My car was still on the shoulder, in pretty much the same condition as I'd left it, although all the rain had covered it with a layer of grime and someone had written ALSO AVAILABLE IN WHITE with a finger on the passenger door. I headed between the Portakabins (apparently deserted, except for Hunt in the office, blowing his nose loudly) onto the site, to retrieve my sleeping bag and my thermos.

The mood of the dig had changed: this time there were no water fights and no cheery shouting. The team was working in grim silence, hunched like a chain gang, keeping a hard, punishingly fast rhythm. I went through the dates in my mind: this was their last week, the motorway people were due to start work on Monday if the injunction was lifted. I saw Mel stop mattocking and straighten up, grimacing, one hand to her spine; she was panting, and her head fell back as if she didn't have the strength left to hold it up, but after a moment she rolled her shoulders, took a breath and heaved up her mattock again. The sky hung gray and heavy, uncomfortably close. Somewhere far away, on the estate, a car alarm's hysterical shrieking went ignored.

The wood was dark and sullen, giving away nothing. I looked at it and realized that I very badly did not want to go in there. My sleeping bag would be sodden by now, and probably colonized by mold or ants or something, and I never used it anyway; it wasn't worth the immensity of that first step into the rich, mossy silence. Maybe one of the archaeologists or the local kids would find it and annex it before it rotted away.

I was already late for work, but even the thought of going in made me tired, and a few more minutes wouldn't make much difference at this stage. I found a semicomfortable position on a tumbledown wall, one foot up to brace myself, and lit a cigarette. A stocky guy with scrubby dark hair-George McSomething, I remembered him vaguely from the interviews-raised his head and saw me. Apparently this gave him an idea: he stuck his trowel into the ground, sat back on his haunches and pulled a flattened smoke packet out of his jeans.

Mark was kneeling on top of a thigh-high bank, scraping at a patch of earth with coiled, frantic energy, but almost before the dark guy fished out a cigarette he had spotted him and was leaping down off the bank, hair flying, and bounding over. "Here, Macker! What the fuck do you think you're doing?"

Macker jumped up guiltily-"Jesus!"-dropped the packet and fumbled for it in the dirt. "I'm having a smoke. What's your problem?"

"You have it on your tea break. Like I told you."

"What's the big deal? I can smoke and trowel at the same time, it takes five seconds to light a fag-"

Mark lost it. "We don't have five seconds to waste. We don't have one second. Do you think you're still in school, you fucking half-wit? Do you think this is all some kind of game, yeah?"

His fists were clenched and he was halfway to a street fighter's crouch. The other archaeologists had stopped working and were watching, open-mouthed and unsure, tools suspended in midair. I wondered if it was going to turn into a brawl, but then Macker forced a laugh and stepped back, raising his hands mockingly. "Relax, man," he said. He held up the cigarette between thumb and finger and reinserted it into the packet with elaborate precision.

Mark kept staring until Macker, taking his time, had knelt down and picked up his trowel and started scraping again. Then he spun around and headed back towards the bank, his shoulders hunched and rigid. Macker scrambled stealthily to his feet and followed, mimicking Mark's springy lope, turning it into a chimpanzee's gallop. He got an edgy snicker from one or two of the others; pleased with himself, he held out his trowel in front of his crotch and thrust his pelvis at Mark's backside. His silhouette against the lowering sky was distorted, grotesque, a creature from some obscene and darkly symbolic Greek frieze. The air hummed with electricity like a power line and his clowning set my teeth on edge. I realized I was digging my nails into the wall. I wanted to handcuff him, smack him in the mouth, anything to make him stop.