But where was he exactly? There had been no map. He only followed the directions he’d been given. Nowhere looked the same in the dark anyway. People who lived in towns didn’t realise how black it was out in the proper country at night. They never saw total darkness like this. So a map would have been useless.

A noise made Rob whirl round suddenly. It sounded like a voice – a garbled word spoken from the darkness, a liquid gabbling from a throat that surely wasn’t human. But then the noise came again and he saw the river. He could see the surges of water bubbling over the rocks, sucking and gurgling through gaps and crevices in the riverbed. He saw the muddy bank and the skeletal outline of a stunted tree growing on the water’s edge.

And something else.

Rob realised with a shock that he could see a pale face caught in the light. It was the mask of a ghoul, white and ghostly, with the unnatural gleam of cheap plastic. He had a glimpse of a profile pulled into a grotesque shape – a gaping mouth, a blank eye, a trickle of blood. It was surely a Halloween joke to scare the children. Just some bad taste prank.

The hairs on the back of Rob’s neck stirred, and he swung his torch wildly across the trees until its beam lit the glittering water rushing between the banks and highlighted the arch of the bridge. His trembling hand swept the light backwards and forwards along the parapet looming above him and probed into the gap between the stones to pick out the ancient trackway. It was half in shadow and half illuminated by his wavering torchlight. It looked like an empty stage, garishly lit, awaiting the next scene of a drama.

Rob had lived in this area all his life and he knew what this place was. Everyone called it the Corpse Bridge.

Friday 1 November

And yet there was so little blood.

Ben Cooper crouched and leaned forward to look more closely. For a moment he felt light-headed from tiredness and almost slipped in the mud on the bank of the river as his head swam. But he recovered himself in time, a hand poised in mid-air almost touching the body. He hoped no one had noticed.

There was certainly a lack of blood. Sometimes a corpse could surprise you like that. At first glance it didn’t seem possible that anyone could be dead, when they’d hardly bled at all. Here there were no more than a few drops on the corner of the stone, a narrow trickle that might just as easily have been a splash of muddy water or a leak from a damaged bottle. Not blood, but a spilled energy drink.

Cooper straightened up again, easing the discomfort in his back. Either way, the body had been drained of its vitality. The life force had departed hours ago.

An upper stretch of the River Dove was rushing under the bridge here. Though barely the width of a stream, the water was running fast as the earlier rain syphoned down off the hills on both sides. The body was trapped in the branches of a sycamore lying close to the surface. To Cooper’s weary eyes, those dark, wet boulders all around it could have been a dozen bodies lying half-submerged. The roaring of the water might have been their cries of pain, that gurgle under a rock a victim’s last, dying breath.

The north side of the bridge was green with mould and fungus. Uneven stone setts on the bridge were lined with dying brambles. Here the river had slippery edges, with no safe footing in the mud, and the body was only accessible on foot through the water. Divers had waded into the river and were now under the bridge attempting to recover the body. The victim had fallen into an awkward, tangled position, and the body was already partially rigid from the onset of rigor mortis.

The initial police response had accessed the bridge using four-wheel-drive vehicles from the Derbyshire side, right down to where a large lump of rock blocked the crossing. The water was shallow enough to have been a ford at one time, but the idea of driving across it had been effectively discouraged.

The bridge itself was much too narrow for vehicles. It was the type of structure generally described as a packhorse bridge, with low parapets and stone setts designed to provide a secure footing for horses. But this bridge had been known for a different function.

It was barely six in the morning when he’d arrived, and still dark by the river. Arc lights had been set up to illuminate the scene, but it might be a while before he got a proper look at the victim. Evidence would become more obvious in daylight. A story might start to emerge then. The story of how one more human being had encountered death.

One of his detective constables, Luke Irvine, had been here at the scene before him. That was the penalty of being on call-out. Irvine was a bit dishevelled and unshaven, which somehow made him seem even younger than he was.

Cooper tended to forget that the younger DCs had only a few years’ experience. They were impressively competent and self-confident – much more than he himself had been at the same age, he felt sure. The other youngster on his team, Becky Hurst, was destined for great things in his estimation. She had that air about her, a quiet determination and absolute focus on what she wanted. Luke was okay, but a little bit rebellious and unpredictable. Somebody would knock those edges off him one day. Or something.

‘Well, as you can see,’ said Irvine, ‘we’ve got a female, aged about thirty-five. Caucasian. She’s not been in the water very long, by the looks of it. There’s a clear head wound, but other than that—’

‘Found by?’

‘Finder’s name is Rob Beresford. Actually, his full name is Robson – as in Robson Green the actor, you know?’

‘Yes.’

‘He’s fairly local. Lives in Earl Sterndale. Mr Beresford says he was walking down here and saw the woman in the water. He had to go back up the trackway a hundred yards or so before he could dial 999 on his mobile.’

‘He was on his own?’ asked Cooper.

‘It seems so. But—’

‘What, Luke?’

Irvine shrugged. ‘Well, you’ll see for yourself when you talk to him, Ben. I know you like to form your own impressions.’

‘Okay.’

‘We’ve got him up the road there. Will you talk to him now?’

‘In a second.’

The River Dove was the boundary not only between two counties, but between the East Midlands and West Midlands. It was the border between limestone country and sandstone too. In daylight the view across the valley made the contrast obvious, with the hills on the Staffordshire side looking so much more gentle and unimpressive compared to the rugged limestone at his back. As far as Cooper was concerned, there was no doubt about it, whatever some Staffordshire people said. Derbyshire had the best hills.

In between, on the flatter and more fertile land in a loop of the river, stood one of Derbyshire’s historic houses, Knowle Abbey – a huge country mansion where the Earls of Manby had lived for generations, surrounded by acres of landscaped parkland. It had always seemed to Cooper like a sort of no man’s land, sitting in its own little world halfway between the two counties, but having little connection with either of them.

There was a Staffordshire Police presence here too, Cooper saw. Their vehicles carried a badge with the Staffordshire knot instead of the Derbyshire coat of arms. It was a strange choice of logo, he’d always thought. The triple loop of the Staffordshire knot was supposed to represent the solution devised by a hangman to execute three felons simultaneously. It didn’t really fit with the current public image the police tried to present. Looking round, Cooper identified a couple of uniformed constables, an officer from Staffordshire’s Major Investigation Department, and a Forensics Investigation van from their station at Leek.

The body of the victim had been tangled in the roots of a tree close to the Derbyshire side. But the River Dove was very narrow here and the county boundary ran right down the middle. He supposed it was possible that part of the body had been lying or floating in Staffordshire’s jurisdiction.