I remember that moment because, if I am honest, I have them so seldom. I am not good at noticing when I'm happy, except in retrospect. My gift, or fatal flaw, is for nostalgia. I have sometimes been accused of demanding perfection, of rejecting heart's desires as soon as I get close enough that the mysterious impressionistic gloss disperses into plain solid dots, but the truth is less simplistic than that. I know very well that perfection is made up of frayed, off-struck mundanities. I suppose you could say my real weakness is a kind of long-sightedness: usually it is only at a distance, and much too late, that I can see the pattern.

Neither of us felt like a pint. Cassie rang Sophie's mobile and gave her the story about recognizing the hair clip from her encyclopedic knowledge of cold cases-I got the sense Sophie didn't really buy it, but didn't much care either way. Then she went home to type up a report for O'Kelly, and I went home with the old file.

I share an apartment in Monkstown with an unspeakable woman named Heather, a civil servant with a little-girl voice that always sounds as though she is about to burst into tears. At first I found it appealing; now it just makes me nervous. I moved in because I liked the idea of living near the sea, the rent was affordable, and I fancied her (five foot nothing, tiny build, big blue eyes, hair down to her arse) and harbored Hollywood-style fantasies of a beautiful relationship blossoming to our mutual amazement. I stay because of inertia and because by the time I discovered her array of neuroses I had started saving for an apartment of my own, and her flat was-even after we both worked out that Harry and Sally were never going to materialize, and she raised my rent-the only one in the greater Dublin area that would allow me to do that.

I unlocked the door, shouted, "Hi," and made a dive for my room. Heather beat me to it: she appeared in the kitchen doorway with incredible speed and quavered, "Hi, Rob, how was your day?" Sometimes I have this mental picture of her sitting in the kitchen hour after hour, folding the hem of the tablecloth into perfect little pleats, poised to leap out of her chair and fasten on to me as soon as she hears my key in the lock.

"Fine," I said, keeping my body language pointed towards my room and unlocking my door (I installed the lock a few months after I moved in, ostensibly to prevent hypothetical burglars from making off with confidential police files). "How are you?"

"Oh, I'm all right," Heather said, pulling her pink fleece dressing gown more closely around herself. The martyred tone meant I had two options: I could say, "Great," and go into my room and close the door, in which case she would sulk and bang pans for days to register her displeasure at my lack of consideration, or I could say, "Are you OK?" in which case I would have to spend the next hour listening to a blow-by-blow account of the outrages perpetrated by her boss or her sinuses or whatever it was that was currently making her feel hard done by.

Fortunately I have an Option C, though it has to be saved for emergencies. "Are you sure?" I said. "There's this awful flu going round at work, and I think I'm coming down with it. I hope you don't get it, too."

"Oh, my God," said Heather, her voice going up another octave and her eyes getting even bigger. "Rob, pet, I so don't mean to be rude, but I'd probably better stay away from you. You know I just get colds so easily."

"I understand," I said reassuringly, and Heather disappeared back into the kitchen, presumably to add horse-sized capsules of vitamin C and echinacea to her frenetically balanced diet. I went into my room and closed the door.

I poured myself a drink-I keep a bottle of vodka and one of tonic behind my books, to avoid cozy convivial "drinkies" with Heather-and spread out the old case file on my desk. My room is not conducive to concentration. The whole building has the cheap, mean-spirited feel of so many new Dublin developments-ceilings a foot too low, frontage flat and mud-colored and hideous in an utterly unoriginal way, bedrooms insultingly narrow as if designed to rub in the fact that you can't afford to be picky-and the developer saw no need to waste insulation on us, so every footstep from above or musical selection from below echoes through our entire flat, and I know far more than I need to about the sexual tastes of the couple next door. Over four years I've more or less got used to it, but I still find all the basic premises of the place offensive.

The ink of the statement sheets was faded and spotty, almost illegible in places, and I tasted fine dust settling on my lips. The two detectives who had headed the case were both retired by this time, but I made a note of their names-Kiernan and McCabe-in case we, or rather Cassie, needed to talk to them at some stage.

One of the most startling things about the case, to modern eyes, is how slow our families were to become worried. Nowadays parents are on the phone to the police as soon as a child's mobile goes unanswered; Missing Persons have become jaded from taking too many reports on children kept after school or lingering over video games. It seems ingenuous to say that the 1980s were a more innocent time, given all that we now know about industrial schools and revered priests and fathers in rocky, lonely corners of the country. But then these were only unthinkable rumors happening somewhere else, people held on to their innocence with a simple and passionate tenacity, and it was perhaps no less real for being chosen and for carrying its own culpability; and Peter's mother called us from the edge of the wood, wiping her hands on her apron, and then left us to our absorbing game and went home to make the tea.

I found Jonathan Devlin in the margins of a minor witness statement, halfway through the pile. Mrs. Pamela Fitzgerald of 27 Knocknaree Drive-oldish, by the cramped, curlicued handwriting-had told the detectives that a group of rough-looking teenagers hung around the edge of the wood, drinking and smoking and courting and sometimes hurling terrible abuse at passersby, and that you weren't safe walking your own road these times, and that what they needed was a good clatter round the ear. Kiernan or McCabe had scribbled names down the side of the page: Cathal Mills, Shane Waters, Jonathan Devlin.

I flipped through the sheets to see if any of them had been interviewed. Outside my door I could hear the rhythmic, invariable sounds of Heather going through her nightly routine: determinedly cleansing and toning and moisturizing, brushing her teeth for the dentist-prescribed three minutes, genteelly blowing her nose an inexplicable number of times. Bang on schedule at five to eleven, she tapped on my door and cooed, "Night-night, Rob," in a coy stage whisper. "Night," I called back, adding a cough at the end.

The three statements were brief and almost identical, except for margin notes that described Waters as "v. nervous" and Mills as "uncoperative" [sic]. Devlin hadn't warranted any comment. On the afternoon of August 14, they had drawn their unemployment assistance and then gone by bus to the pictures in Stillorgan. They had got back to Knocknaree around seven-when we were already late for tea-and gone drinking in a field near the wood till around midnight. Yes, they had seen the searchers, but they had simply moved behind a hedge to be out of sight. No, they hadn't seen anything else unusual. No, they hadn't seen anyone who could confirm their whereabouts that day, but Mills had offered (presumably in a spirit of sarcasm, but they took him up on it) to lead the detectives to the field and show them the empty cider cans, which did indeed prove to be located in the spot he identified. The young man who had been working the box office at the Stillorgan cinema appeared to be under the influence of controlled substances and wasn't sure whether he remembered the three guys or not, even when the detectives searched his pockets and gave him a stern lecture about the evils of drugs.