Tom Fletcher loosened his tie. His neck felt damp, due partly to the summer heat. He watched the photographer take another shot, using flash despite the sunlight streaming through glass panels in the roof. The photographer stood back and turned to him.

‘Is that the worst you’ve seen?’

Fletcher nodded. In eight years with the Cambridge police, it was the nastiest death he’d encountered. He brushed a fly away from his face.

He was standing in a large hangar-type building used as a showroom for farm machinery. In front of him was a line of yellow tape set up by the accident investigators, then a half-circle of tractors for sale. The pairs of headlamps all seemed to be watching something.

There was a different machine in the centre of the group. It was a heavy-duty mechanical shredder, designed for cutting up tree branches - really just a set of blades inside a chute that a man could fit into. A man had. A pair of legs was projecting from it, the feet twisted at unnatural angles. Fletcher noticed something puzzling.

The shoes. He studied the shoes.

The legs belonged to a young guy named Jake Skerrit, aged twenty-two and fresh out of University. Jake worked as a management trainee for Breakman Machinery, a farm equipment dealer in the fenland north of Cambridge. The staff here all agreed that Jake was a hard worker who did paperwork in the depot on Sunday nights. They added that he liked fooling around with dangerous machines. Today being Monday, his corpse had been found by the security man who unlocked the building in the morning.

The body wasn’t completely shredded, because a safety system kicked in when the blades finally reached his shoulders. So the face, wedged up against the steel intake, was still partially intact - but the blades had destroyed his arms and taken a big chunk from the side of his skull. The floor on the other side of the chute, where the machine would normally spit out its wood chips, was spattered with human debris: hair, bits of bone, two complete fingers, a shirt cuff and something that looked to Fletcher like an earlobe. Under the shredder itself, a circle of blood was in the final stage of thickening, like road tar. The flies were really gathering.

Fletcher was fascinated by Jake’s shoes.

He guessed the Health and Safety people would try to prosecute, because the Breakman staff habitually left machines with keys in the ignition. Still, the death seemed like a genuine accident - one to add to the sixty other deaths involving farm machinery that happen each year in Britain. A police surgeon had attended as a formality, and a post-mortem was booked. Fletcher had other cases pending, and maybe he should have left this alone - maybe his presence should have been just another formality - but the shoes wouldn’t let him.

He watched as the investigators in their white paper suits rolled up the tape, and the photographer began packing away his kit. Two morose-looking individuals came into the hangar, men known to the police as the Glum Reapers: specialised operatives from an undertaker in Cambridge. One was carrying a body bag, and the other was swinging a shovel.

Fletcher turned away, still thinking about the shoes. He glanced up at the CCTV camera bolted to the wall, perfectly placed to record the death, its red light blinking.