The camera swung back again, wobbled, and focused on a group of young people standing in the road, their faces bright with excitement. Fry thought one of them could have been the girl she’d seen later with blood running down her face.

‘Run it back to the horses,’ she said.

Abbott replayed it and froze the image at the point where the two riders could be seen most clearly. Fry gazed at the picture for a long time. In truth, it told her very little. She could see the general colour of the horses. She could tell that the riders weren’t wearing red coats, but tweed jackets and black helmets. But at least that was something.

At the bottom of the screen, the date stamp said it was zero-eight thirty-six, an hour before the first of the mounted hunt were supposed to have arrived for the meet. If she could discover where the cameraman was standing, she could work out whether the riders were going towards the location where Patrick Rawson had died, or coming away from it.

‘So much for our Mrs Forbes and Mr Widdowson,’ she said.

COOPER GOT A call from Fry as he left Birchlow, and decided to take the route across Longstone Edge itself. All along the edge were lay-bys, retired couples sitting in their little Smart cars to eat sandwiches and drink tea, enjoying the tranquillity of the Peak District before the Easter rush of tourists.

Driving along the edge was the closest thing to flying Cooper could think of, without having to queue at security and cram yourself into an economy-class cabin. Looking out of the passenger window of the car, he couldn’t see any sign of the ground, just an open expanse way out into space, and a glimpse of the valley down below. Coasting down the Longstone Edge road was just like being in an aircraft coming in to land, watching the earth growing gradually closer.

It wasn’t a good idea to take your eyes off the road and admire the scenery for too long, though. A while ago, a woman had driven her car off the edge somewhere about here, ending up lodged in the trees below the road. She’d stayed there for twenty-four hours, too, trapped in her car as motorists passed on the road without seeing her.

At the top, he heard the rumble of an engine, the whine of gears, the rattle of falling rock. Another quarry truck was labouring up the long track to the opencast workings. A scattering of sheep ambled along the roadside, where the dry-stone walls had fallen or vanished altogether. Their fleeces were thick and heavy after the winter, making their movements ungainly, like a bunch of walking armchairs. They didn’t seem a bit concerned to be sharing their stretch of road with those massive haulage lorries.

When Cooper appeared at the scene to get the latest update, Fry described the video footage received from the hunt saboteur.

‘A shout?’ he said.