He felt a familiar object bump his foot by the door. This strangely shaped lump of stone had stood by the back door of the farmhouse for decades, maybe for centuries. It was roughly rounded, with a broader base and a hollow in the middle, with a hole hacked through the bottom.

Everyone had used the stone as a boot scraper or a container for loose screws, until Cooper had seen a photograph in a local history book of an identical object. It was described in the caption as an Iron Age quern, used for grinding corn. It was two thousand years old.

The quern still stood by the back door of Bridge End Farm, unaltered from the last day it had been used for grinding corn. It had been emptied of screws and cleaned up. No boots were scraped on it now. The quern had always stood where it was, as far as anybody knew, so there was no suggestion of moving it. It was preserved for posterity. But nobody used it any more.

Before Cooper could get out of the house, Kate called to him from the passageway.

‘Ben, Helen Milner rang earlier this evening. She sounded a bit upset. She said you were supposed to be meeting her. I told her you were probably working.’

Cooper winced. Helen would have turned up at the rugby club looking for him – they’d had a date tonight. They’d been going out together for only two months. He knew all too well how she would interpret the way he had stood her up.

‘I meant to phone her, but I completely forgot.’

‘That’s what I thought,’ said Kate. ‘And Helen didn’t sound too surprised, either.’

There was no one waiting at home for Diane Fry when she pulled on to the drive at Grosvenor Avenue. The old house was converted into flats and bedsits, and her neighbours were mostly students that she rarely saw. They seem to spend most of their time in the pub.

Her room was cold, with a peculiar damp chill that seeped from the walls even in summer. She was already realizing what an uncomfortable, depressing experience a winter in Edendale was going to be. The three-bar electric fire barely chased the chill from the room. And it ate money from the meter at an alarming rate.