"It's like having a puppy," I told Sophie. Helen looked shocked.

"Yes, but a pedigree one," Cassie said cheerfully.

As we headed back across the site towards the car (my shoes were a mess, just like Mark had said they would be-there was red-brown muck grained into every seam-and they had been fairly nice shoes; I comforted myself with the thought that the killer's footwear would be in the same unmistakable condition), I looked back at the wood and saw that flutter of white again: Sophie and Helen and the boy tech, moving back and forth among the trees as silently and intently as ghosts.

4

The Cameron Dance Academy was above a video shop in Stillorgan. On the street outside, three kids in baggy trousers were flipping skateboards on and off a low wall and yelling. The assistant teacher-an extremely pretty young woman called Louise, in a black leotard and black pointe shoes and a full, calf-length black skirt; Cassie gave me an amused look as we followed her up the stairs-let us in and told us Simone Cameron was just finishing up a class, so we waited on the landing.

Cassie drifted over to a cork notice-board on the wall, and I looked around. There were two dance studios, with little round windows in the doors: in one, Louise was showing a bunch of toddlers how to be butterflies or birds or something; in the other, a dozen little girls in white leotards and pink tights were crossing the floor in pairs, in a series of jumps and twirls, to the "Valse des Fleurs" on an old scratchy record player. As far as I could tell there was, to put it mildly, a wide range of ability. The woman teaching them had white hair pulled back in a tight bun, but her body was as spare and straight as a young athlete's; she was wearing the same black outfit as Louise and holding a pointer, tapping at the girls' ankles and shoulders and calling instructions.

"Look at this," Cassie said quietly.

The poster showed Katy Devlin, though it took me a second to recognize her. She was wearing a gauzy white smock and had one leg raised behind her in an effortless, impossible arc. Below her it said, in a large font, "Send Katy to the Royal Ballet School! Help Her Make Us Proud!" and gave the details of the fund-raiser: St. Alban's Parish Hall, 20 June, 7:00 p.m., An Evening of Dance with the Pupils of the Cameron Dance Academy. Tickets a10/a7. All Proceeds will Go to Pay Katy's Fees. I wondered what would happen to the money now.

Under the poster was a newspaper clipping, with an arty soft-focus shot of Katy at the barre; her eyes, in the mirror, gazed out at the photographer with an ageless, intent gravity. DUBLIN'S TINY DANCER TAKES WING, The Irish Times, 23 June: "'I guess I'll miss my family, but I still can't wait,' Katy says. 'I've wanted to be a dancer ever since I was six. I can't believe I'm really going. Sometimes when I wake up I think maybe I dreamed it.'" No doubt the article had brought in donations towards Katy's fees-another thing we'd have to check up on-but it had done us no favors at all: pedophiles read morning papers, too, and it was an eye-catching photo, and the field of potential suspects had just widened to include most of the country. I glanced at the other notices: tutu for sale, size 7-8; would anyone living in the Blackrock area be interested in setting up a carpool to and from the intermediate class?

The studio door opened and a flood of matching little girls streamed past us, all chattering and shoving and shrieking at once. "Can I help you?" Simone Cameron asked, in the doorway.

She had a beautiful voice, deep as a man's without being in the least mannish, and she was older than I had thought: her face was bony and deeply, intricately lined. I realized that she probably took us for parents coming to ask about dance classes for our daughter, and for a moment I had a wild impulse to play along with it, ask about fees and schedules and go away, leave her her illusion and her star pupil a little longer.

"Ms. Cameron?"

"Simone, please," she said. She had extraordinary eyes, almost golden, huge and heavy-lidded.

"I'm Detective Ryan, and this is Detective Maddox," I said for the thousandth time that day. "Could we speak to you for a few minutes?"

She brought us into the studio and set out three chairs in a corner. A mirror took up the whole of one long wall, three barres running along it at different heights, and I kept catching my own movements out of the corner of my eye. I angled my chair so I couldn't see it.

I told Simone about Katy-it was definitely my turn to do this part. I had expected her to cry, I think, but she didn't: her head went back a little and the lines in her face seemed to get even deeper, but that was all.

"You saw Katy in class on Monday evening, didn't you?" I said. "How did she seem?"

Very few people can hold a silence, but Simone Cameron was unusual: she waited, not moving, one arm thrown over the back of her chair, until she was ready to speak. After a long time she said, "Very much as usual. Slightly overexcited-it was a few minutes before she could settle and concentrate-but this was natural: she was to leave for the Royal Ballet School in a few weeks. She'd been growing more and more excited about it all summer." She turned her head away, very slightly. "She missed her class yesterday evening, but I simply assumed she was ill again. If I had rung her parents…"

"By yesterday evening she was dead," Cassie said gently. "There was nothing you could have done."

"Ill again?" I asked. "Had she been ill recently?"

Simone shook her head. "Not recently, no. But she isn't a strong child." Her eyelids dropped for a moment, hooding her eyes: "Wasn't." Then she looked up at me again. "I've taught Katy for six years now. For several of those years, beginning when she was perhaps nine, she was ill very often. So was her sister Jessica, but her illnesses were colds, coughs-she, I think, is simply delicate. Katy suffered from periods of vomiting, diarrhea. Sometimes it was serious enough to need hospitalization. The doctors thought it was some form of chronic gastritis. She should have gone to the Royal Ballet School last year, you know, but she had an acute attack at the end of the summer, and they operated on her to find out more; by the time she recovered, it was too far into the term for her to catch up. She had to reaudition this spring."

"But recently these attacks had disappeared?" I asked. We would need Katy's medical records, fast.

Simone smiled, remembering; it was a small, wrenching thing, and her eyes flicked away from us. "I was worried about whether she would be healthy enough for the training-dancers can't afford to miss many classes through illness. When Katy was accepted again this year, I kept her after class one day and warned her that she would have to keep seeing a doctor, to find out what was wrong. Katy listened, and then she shook her head and said-very solemnly, like a vow-'I'm not going to get sick any more.' I tried to impress upon her that this wasn't something she could ignore, that her career might depend on this, but that was all she would say. And, in fact, she hasn't been ill since. I thought perhaps she had simply outgrown whatever it was; but the will can be a powerful thing, and Katy is-was-strong-willed."

The other class was letting out; I heard parents' voices on the landing, another rush of small feet and chatter. "You taught Jessica as well?" Cassie said. "Did she audition for the Royal Ballet School?"

In the early stages of an investigation, unless you have an obvious suspect, all you can do is find out as much about the victim's life as possible and hope something sets off alarm bells; and I was pretty sure Cassie was right, we needed to know more about the Devlin family. And Simone Cameron wanted to talk. We see this a lot, people desperate to keep talking because when they stop we will leave and they will be left alone with what has happened. We listen and nod and sympathize, and file away everything they say.