Skirting the edge of the hollow to reach the base of the tower, he wrinkled his nose as a trace of something acrid and familiar reached his nostrils. Could he be mistaken? Were his senses playing tricks on him again? No, the smell was quite distinct and recognizable. Cal and Stride’s van had smelled of chicken curry. Yet the Hammond Tower smelled of petrol.

From the tower, a steep track ran down to a ledge below the Cat Stones. Cooper scrambled down the track, puzzled at the origin of the petrol smell. But as he moved away from the tower, the smell dissipated. It was lingering around the wall of the tower itself.

He looked at the outcrop of rocks above him. They formed one of the biggest of the cat shapes – a pile of wind-sculpted blocks of gritstone perched on a softer layer that had been worn almost completely away by wind and water. A yawning gap had been left underneath on this side – a great empty gash that made you wonder how the cat-shaped blocks stayed hanging in that precarious position. One day, the cat’s legs would give way under the weight of rock and it would topple into the dale, forfeiting all of its nine lives in one go.

Cooper peered under the overhang. The cavity went deep under the rocks, six feet in, the height getting less as it receded to the back, a very shallow cave formed by the weathering of the stone. On the outer edge lay a handful of damp, grey feathers, where some predator had stopped long enough to dismember a wood pigeon. Cooper’s nose twitched. There was something else here. Not petrol now, but something that smelled stale and unpleasant.

He crouched and ducked his head below the rock, then waited for his eyes to adjust to the darkness. The smell was more powerful and unmistakable. At these moments, he always remembered his first shift sergeant telling him to learn to breathe through his mouth at a death scene. If you were going to deal with dead bodies often, he said, it helped if you had a sinus problem, or chronic nasal congestion.

Cooper saw a hand, then an arm. Where the body touched the rock, the surface was stained dark with leaking fluids. The muscles and tissues had shrunk inwards away from the skin, leaving it hanging loose, like the flesh of an old, old woman. On one edge of the forearm, the skin had burst open, exposing the layers of muscle and fat underneath. Next, he noticed the dark snakes of hair that lay around the head. Although the ledge was dry, enough moisture had been supplied by the body’s own fluids to support the process of putrefaction. By now, decomposition was well advanced, despite the cool air of the White Peak autumn. The body had been lying here a few weeks.