I managed to keep at least three cars behind him the whole time, and knowing the rough direction he was headed meant I could drop right back: after a while, I was two or three bends off the pace, and only catching the occasional glimpse of his blue Lexus up front – which meant, unless he stopped dead, he’d never see me tailing him.

Finally, I got to the turning.

The mill was immediately visible the moment I came off the road, a restored stone building with two vast chimneys and a waterwheel on the side. It was flanked by fields on the left and a maze of old, terraced cottages on the right, and the car park was rammed. As I came down the drive towards it, I could see Mills’s Lexus already pulling into a space next to a pair of huge windows: on the other side of the glass was a restaurant, mothers at tables with young babies, and a play area for toddlers at the far end.

What the hell is he doing here?

I slowed down, not wanting to enter the car park as he was heading for the mill, but once he’d gone into the main doors I found the first space I could and swung the Audi in, front end first, so the damage was hidden from view. I grabbed a baseball cap from the boot and swapped my sweater – the same one I’d been wearing when Mills and I met at Black Gale – for a windbreaker. It wasn’t much of a disguise, but it was something.

I made my way inside.

Keeping to a wall, so I only had to be aware of what was around me on one side, I moved through the mill from front to back. The restaurant was heaving, every table occupied, but I couldn’t see him seated anywhere, or in the queue for food; he wasn’t in the next part of the building either, where a gift shop occupied one side and a museum the other. I couldn’t get into the museum without paying, but I could see enough of it through a series of windows.

I got to a set of stairs, with signs directing visitors to conference and reception rooms, and then realized I’d missed a door: it went through to a temporary exhibit full of black-and-white photos documenting Keygrave’s years as a textile mill.

He was in there.

I backed up, watching him through a small glass panel in the door. There was no one else in the room except him. At first I assumed that was the whole point, that he was here because he was meeting someone and knew the exhibit would be quiet, but he didn’t seem remotely interested in anything but the photos.

So was this really what he’d come all this way for?

A photography exhibition?

About ten minutes later, his mobile chimed.