In the cottage’s living room, they lifted more carpets, checked under more sideboards, dug behind and underneath the upholstery on the couch, probing through welters of crumbs and tattered newspaper. They prodded thick tufts of fluff gathered behind radiators, and pried loose skirting boards away, only for mice and cockroaches to scamper free. Some shelves next to the television were stacked with unmarked DVDs. They played a few of these and found they were nothing more than pirate copies of recent movies. Peabody suggested that this was another charge they could add, but Lucy called it ‘Mickey Mouse stuff’.

She was getting tired herself now, and deeply frustrated. The clock was ticking on her prisoners, and she couldn’t keep these officers on duty for ever. When she glanced at her watch and saw that it was nearly three in the morning, she was ready to call it off. She was standing at the top of the cottage stairs contemplating this, when a voice came up to her from below. She went back down and found PC Darlington in the doorway to the ground-floor privy.

‘Could this be what we’re looking for?’ Darlington wondered.

Curious, Lucy stuck her head into the cubicle, where another PC, a tall lad, had stood on the toilet lid to check inside the cistern, which was high on the wall, and in so doing had accidentally hit the ceiling with the top of his head, dislodging a concealed but loose panel, from behind which a bulky plastic sack had tumbled. He’d already opened the sack and discovered maybe a hundred sachets of white powder, which he offered to Lucy in two gloved hands.

For the first time in two or three hours, she smiled.

Forty minutes later, Lucy was back in the Custody Suite at Robber’s Row police station. A few of the lesser miscreants, those who didn’t own dogs themselves, were already lined at the counter, being charged with attending a dog-fight and making bets.

DI Beardmore, who ought to have gone home hours ago, stood to one side, arms folded, looking sallow-cheeked. He’d even removed his jacket and tie and unbuttoned his collar, which was not his normal form. When he saw Lucy, he frowned all the more.

‘Can we get this show on the road, please?’ he said grumpily. ‘We’re running out of space in here, Lucy. The night shift have started nicking real criminals and we’ve nowhere to put them.’

‘Sir … Mahoney’s a real criminal.’ And she told him what they’d found at the cottage, and the phone-calls she’d made afterwards as she’d headed back here from Wellspring Lane.

A short time later, she walked down the cell corridor, produced a bunch of keys and unlocked one of the doors. Inside, Mahoney was lying on the narrow mattress, arms folded behind his head. He sat up and yawned. ‘About fucking time.’