There was a door on my left. I forced myself to go through it. A child’s bedroom, a boy young enough still to have Lego and action figures scattered on the floor. The bed was neatly made with no-nonsense blue and purple matching pillow cases and duvet cover. The boy had liked Ben 10 and Chelsea FC enough to put their posters on his walls. There was a smell of dust, but none of the mildew and damp that I would associate with a long-abandoned house. The master bedroom was the same, the bed neatly made up, an air of dry dustiness but no cobwebs in the corners of the ceiling. The digital alarm clock by the bed had stopped despite being plugged into the mains. When I picked it up, white sand trickled out from a bottom seam. I replaced it carefully and made a mental note to check it later.

The main room at the back of the house was the nursery. Beatrix Potter wallpaper, a cot, playpen. A hypoallergenic wooden mobile from Galt’s Educational Toys shivered in the draft from the open door. As with the other rooms, there was no sign of a struggle or even a rapid departure; everything was neatly squared away. Unnatural in a child’s bedroom. Equally unnatural was the lack of shower mould in the bathroom, or the dusty non-smell of the water in the cistern.

The last room on the top floor was what an estate agent would call a ‘half-bedroom’ suitable for small children or midgets with agoraphobia. This had been converted into a mini-office with a two-year-old Dell PC and, unsurprisingly, an IKEA filing cabinet and desk lamp. When I touched the computer I got a flash of dust and ozone, a vestigium that I recognised from the master bedroom. I popped open the side of the case and found the same white sand inside. I rubbed it between my fingers. It was very fine, powdery even but definitely granular and flecked with gold. I was about to pull the motherboard when Nightingale arrived in the doorway.

‘What the hell are you waiting for?’ he hissed.

‘I’m checking the computer,’ I said.

He hesitated, pushed his hair back off his forehead. ‘Leave it,’ he said. ‘Only one last place to look.’

I’d have to remember to come back with an evidence bag and grab the whole computer.

There was a door in the hallway that led to a set of narrow stairs heading down. The steps were worn hardwood planks that I guessed had been laid down when the house was built. A bare bulb dangled just inside the door, half-blinding me and making the gloom at the base of the stairs more intense.

The basement, I thought; why am I not surprised?

‘Well,’ said Nightingale, ‘we’re not getting any younger.’

I was happy to let him go first.