I put in a call for some lucky searchers to do bin duty—the flat was near enough to underground that I had to go outside to get a signal on my phone; Conor wouldn’t have been able to talk to his friends even if he had had any. Then we moved on to the sitting room.

Even with the lights on, the room was dim. The window, at head-level, looked out on a flat gray wall; I had to crane my neck sideways to catch a narrow rectangle of sky, birds whirling against heavy cloud. The most promising stuff—a monster computer with cornflakes in the keyboard, a battered mobile—was on Conor’s desk, and it was stuff we couldn’t touch without Kieran. Beside the desk was an old wooden fruit crate, with a tattered label of a dark-haired girl holding up an orange and smiling. I flipped the lid off. Inside was Conor’s stash of souvenirs.

A blue checked scarf, faded from washing, with a few long pale hairs still caught in the weave. A half-burnt green candle in a glass jar, filling the box with the sweet, nostalgic scent of ripe apples. A page from a palm-sized notepad, crumples carefully smoothed out: a phone doodle, fast strong strokes, a rugby player running with the ball in his elbow. The mug, a cracked tea-stained thing painted with poppies. The handful of elastic bands, arranged as neatly as treasure. A kid’s crayon drawing, four yellow heads, blue sky, birds overhead and black cat sprawled in a flowering tree. A green plastic magnet shaped like an X, faded and chewed. A dark-blue pen with gold curly writing: Golden Bay Resort—your door to Paradise!

I reached out one finger and pushed the scarf away from the bottom corner of the drawing. EMMA, in those wobbly capitals, and beside it the date. The rust-brown that smeared the sky and the flowers wasn’t paint. She had drawn the picture on Monday, probably in school, with a handful of hours left in her life.

There was a long silence. We knelt on the floor, smelling wood and apples.

“So,” I said. “There’s our proof. He was in the house the night they died.”

Richie said, “I know that.”

Another silence, this one stretched tighter, while we each waited for the other to break it. Upstairs, high heels went clicking sharply across a bare floor. “OK,” I said, and fitted the lid gently onto the crate. “OK. Let’s bag it, tag it and move on.”

The ancient orange sofa was just about visible under jumpers, DVDs, empty plastic bags. We worked our way through the layers, checking for blood and shaking things out and dumping them onto the floor. “For Christ’s sake,” I said, unearthing a TV guide for the beginning of June and a half-full packet of salt and vinegar crisps. “Look at this.”

Richie gave a wry grin and held up a wad of paper towel that had been used to clean up something like coffee. “Seen worse.”