Cooper saw that he’d been right. There were so many visitors trying to get into Matlock Bath that by five o’clock all the car parks in the village were full. Police officers in yellow jackets were directing long queues of motorists to a park-and-ride facility at the rugby club a mile down the road. The pavements were packed with people queuing at the fish-and-chip shops or eating out of paper packages as they leaned over the railings to gaze at the river, throwing their last few chips to the ducks. Many of the crowd were family groups, young children sitting in pushchairs or strapped to the parents in carriers.

It had already been gloomy enough by half past four to use sidelights as they drove down from Edendale. On the way here, the mood had been sombre. Dead leaves had filled the lay-bys like a yellow tide.

‘I have to remind you that we’re here unofficially,’ said Fry. ‘Strictly speaking, you’re off duty.’

Cooper nodded. ‘We understand that, Diane.’

‘No overtime, then?’ said Murfin.

‘No overtime, Gavin. Sorry.’

Murfin shrugged. ‘It gets me out of the house. And it means you can’t tell me not to eat fish and chips while I’m working, right?’

‘Right.’ Fry looked at Kotsev. ‘Georgi? There’s no obligation on you to be here at all.’

‘What else would I be doing? Sitting in my hotel watching English television? I wish to be part of the team.’

‘Thanks, Georgi.’

‘And I’m not to beat up any suspects, OK?’

Fry glanced at him, seemed to recognize that he was joking, and let it pass.

‘I’ve told the inspector in charge of the uniformed operation that we’re here, but I didn’t give him any more details than he needs to know. He’s far too busy to bother about us, anyway. He’s expecting a crowd of six thousand people and a lot of traffic problems. All he’s got to handle it are a dozen bobbies and a few CSOs.’

‘So what are we looking for exactly?’ said Murfin.

‘Brian Mullen. And, I hope, Luanne.’

Cooper coughed uneasily. ‘Diane, if your theory about Brian Mullen is right, what will happen to the child? Will she be sent back to Bulgaria? Surely she wouldn’t have to go back to her real father after all?’

But Fry’s face was hard, giving nothing away. ‘That won’t be our decision to make. All we have to do is find them.’

‘So our responsibility stops there, does it?’

‘Ben, I hope you’re not going all social worker on me again.’

‘But don’t you sometimes wonder what happens to people afterwards – I mean, when we’ve done our job and the courts have done theirs? Don’t you worry that all you’ve done is make a whole lot of people’s lives even worse? Do you always sleep properly at night, Diane?’

‘Yes, like a log.’