‘Not a whole lot.’

He noticed Petra looking over his shoulder. ‘Incoming, watch out,’ she said.

He turned, and saw the chief constable leading in the missing girl’s family.

From somewhere, he dragged together a one-minute presentation of the evidence he had just been told about. He hoped it would sound like he was familiar with every aspect of it. He watched as Beatrice’s father translated his words for the benefit of Mrs Ulbricht.

‘We are doing everything we can,’ Gillard said. It sounded like an apology.

‘Who was it who was impersonating my daughter, wearing her clothes and carrying her violin?’ Mr Ulbricht asked. It was an entirely reasonable question. Gillard just wished he had an answer.

‘We’re still working on that.’

Mrs Ulbricht looked directly at him. She had pale blue eyes and quite chiselled cheekbones beneath her silvery blonde hair.

‘Do you think our daughter is still alive?’ she asked in accented English.

‘There is hope,’ he said. But in truth there wasn’t much.

It was a disconsolate DCI Gillard who returned to the incident room, looking for something – anything – to distract him from his gloom over the case. DC Carl Hoskins looked to be afflicted by the same miasma. He was sitting slumped over his terminal, playing and replaying some very dark CCTV footage.

‘What’ve you got there, Carl?’

‘Probably nothing. This is a camera from a residential address in Westmeare, on a side road not far from the bus stop where we think Beatrice was waiting. There are only two vehicle movements on the side road during that time, one of which is from the drive where the camera is located. But look at this,’ he said, pointing the tip of the pen at something in the top left-hand corner of the fisheye lens image. ‘That is a concave blind spot mirror, for the householder to be able to pull out and see traffic coming from the left.’

‘The left would be towards the main road?’ Gillard asked.

Hoskins nodded. ‘You can see the passing of vehicles on Shere Road as kind of dark dots preceded by the halo of headlamps. They are absolutely tiny. If we were in the original Blade Runner then I’d just be able to zoom right in, and identify every vehicle that passed.’

‘Yeah, but at least we’re not forced to have sex with robots.’

‘Huh, you’ve clearly not tried to get my Brenda going before an early shift,’ Hoskins muttered.

‘Too much information, Carl,’ Gillard replied, then added, ‘Unlike almost every other part of this bloody case.’ He sighed heavily. ‘I think we’ve got some image enhancement software in-house now, I’ll check with Rob Townsend.’

Gillard found the research intelligence officer slouched in the surveillance suite, yawning extravagantly, sipping some posh bought-in coffee. ‘Yes, I’ve got a 2019 version of Close Focus,’ he said. ‘It’s supposed to be the best there is.’ He had huge bags under his eyes.

‘Well, we’ve got a real challenge for it.’ Gillard rang back to the incident room, and got Hoskins to email the CCTV link to Townsend. The young detective constable used the largest, most high-definition screen in the room, and pulled up the half-hour footage. Even on this screen, the blind spot mirror was no bigger than a thumbnail at the edge of the image.