What about his study, then? I’d glanced inside the first time I was in the flat and it surely wouldn’t hurt to take a quick look at the business end of things. I went over to the door on the far side of the living room. ‘Hawthorne …?’ I still called out his name before I went in, knowing there would be no reply. It crossed my mind that there might be security cameras concealed in the flat and that even now Hawthorne or Kevin might be watching me. I tried to look casual. I just need a piece of paper to jot down a few notes about the case – that’s what I told my invisible audience. There was no other reason for me to be opening the drawers of his desk. Nothing personal.

The study was exactly how I remembered it – a desk up against a wall, two computers with strange brand names I’d never heard of, different bits of machinery plugged into the various ports and sockets, a tangle of wires. There were no papers or notepads on the surface, just a paperback copy of The Great Gatsby with several corners folded down to keep the place. I guessed he was reading it with his book club. I examined the shelves, but his choice of books was too diverse to tell me anything: literary fiction, thrillers, classics … everything from Dan Brown to Dostoyevsky. Nothing here by me.

There were eight or nine framed photographs that were more interesting. Half of them were shots of William in different guises – at home, at school, some of them taken with his mother. Hawthorne also had a framed portrait of his wife that stood slightly apart from the rest. This wasn’t a casual snap. It had been taken with a great deal of attention to the light, to the shape of her hair, to her pose. It was a picture you would take of somebody you loved. Three more photographs provided an intriguing record of Hawthorne’s past life, although they didn’t give me very much in the way of facts. Here he was aged about twelve, in short trousers, standing between two adults. One was a uniformed police officer – a sergeant, I think. The other was a woman wearing her Sunday best. His parents? They were both strangely old-fashioned, standing very formally – and they didn’t look anything like him. As for Hawthorne, there was already something vaguely otherworldly about him. He was holding their hands, but there was no emotion in his face. It was as if he was simply doing what he was told.

The next image showed Hawthorne now dressed as a police constable, perhaps at some sort of graduation ceremony. He was trying to smile for the camera, but he only managed to look awkward. Physically, he hadn’t changed much in twenty years: he had just become more menacing as time passed. And finally, here he was with a man of about his own age, both of them holding glasses. The picture had been taken at a pub – I could make out the umbrellas – with a river in the background. It wasn’t the Thames. I got a feeling that this was outside London. I took out my phone and took a picture of the picture. Maybe I could identify the location another time.