The service was beautiful. The church was full of people who’d known Joe, as well as people who hadn’t. Troy was there, and so were Jemima and some of their other classmates. Lots of teachers came, including, of course, Ms Duke, who was in the front row next to Jasper. He had taken my hand, and looked into my eyes, and said, ‘Ariel, I’ll never, ever be able to thank you enough for finding my Joe.’

I was taller than he was. I’d shaken my head, rejecting his thanks.

‘It was Troy too. We just had a feeling.’

I hadn’t really been able to explain what had happened: Troy and I had talked about meeting by accident in the little room, talking about Joe (my reason was because of my babysitting for the girls; Troy’s was obvious), and then looking at the wall panel and unscrewing it on impulse. And finding, as well as the bones, which were all that was left of his body, Joe’s schoolbag and the football trophy which, it turned out, still had fingerprints and Joe’s DNA on it. I’d told the police to check the fingerprints against my father’s, inventing a drunk semi-confession he had once made, and, when they did, he’d been arrested at an apartment in Inverness where he lived with a girlfriend who, it transpired, had had no idea that he had two daughters and a grandson.

There were traces of various chemicals down there. The wall cavity had been big enough to fit a fifteen-year-old boy inside it, and (the police surmised) Dad had gone back with the right substances from work and used them to minimize the odour of decomposition. He couldn’t have hidden it entirely, of course, but the cavity was ventilated by the air-conditioning system, and Piet, among others, remembered the drains outside being cleared because of a smell a couple of months later. No one had made the connection to the missing boy.

We would never know exactly what had happened between them unless Dad decided to talk, but we knew enough. For some reason my father had killed Joe. Not just because he spilled a drink on him, though, surely? It was the one time Joe hadn’t been able to come back and report the details. I was wondering about the old unlucky-punch theory that we’d tried to fit to Lucas, and then Troy. Would that explain why Dad had always been so careful to punch walls instead of people?

Whatever the truth, this was why I couldn’t allow Jasper to thank me. I was the daughter of the man who’d killed his son. Jasper seemed able not to hold it against me. So did Gus and Abby, and Ms Duke had been entirely amazing. Joe’s mum Claire, however, was avoiding me and I didn’t blame her.