A phone call cut into Gillard’s slumber. He was shocked to see that it was a quarter to eleven on Saturday morning. He answered sleepily, propping himself up in bed. ‘Hello Claire, any news?’

‘We’ve picked up a text from Sam’s phone to your work mobile.’

Gillard was instantly awake, and very glad that Claire had the good sense to monitor traffic over the phone he’d been forced to surrender. ‘What did he say?’

‘He said that she is “under the bridge”.’

‘I mean what exactly did he say?’

She read out the exact text.

Under the bridge/ That’s where you’ll find her/ cold, with the fishes/ drowned by your own hand. IC

‘Shit.’ The only bridges that he could think of were at Lacey Dutton, the Loxcombe and the Gorlaston, near which two bodies had already been recovered. Could she be alive if she was there? It could equally be a bridge near where they lived in the Banstead or Chipstead area, anywhere over a river where fish could be found.

‘Craig, we’re tracing Sam’s phone as we speak. Maximum priority. I’d pre-arranged it with the service provider even though the phone has been off since she disappeared. We should get a cell site analysis within the hour.’

Gillard rubbed his face, trying to coax his brain to perform. ‘We can do better, Claire. There’s GPS on it—’

‘The Google geolocation is encrypted though,’ she said. ‘We tried this before, it takes weeks and the involvement of lawyers—’

‘No, listen. Sam has the Android Find My Phone app on her laptop, which CSI has. We don’t have to break into the Google geolocation. The GPS data is copied into the app. Speak to Rob Townsend, he knows how to do it. We can extract the data remotely, unless the phone has been tampered with and some of the apps close down.’ He picked his way through the various bits of paper on the bedside table until he found Sam’s laptop password. He then read it out to Claire. ‘CSI may already have got into the device, but if not, this will get you in.’

‘Brilliant,’ Claire said. ‘Okay, I’ll get onto that. What are you going to do?’

‘What can I do? I’m going to drive over to Lacey Dutton and have a look around the two bridges, maybe get some ideas.’

Gillard hung up and rubbed his face. He’d been awake until at least five, tossing over in his mind all the various possibilities. That he’d had fallen asleep until mid-morning shocked him.

The detective was in the shower when the phone went fifteen minutes later. Heedless of the water over the bedroom carpet, he lurched out of the cubicle and grabbed his mobile. It was Claire.

‘We’ve got a trace,’ she said excitedly. ‘You’re not going to believe this, but Sam’s phone was on Sandy Lane, just outside the University of Guildford Law Department, when that message was sent.’

‘What?’ Gillard knew the building. Just two minutes’ walk from Mount Browne. Sandy Lane was the shared access road to Surrey Police headquarters. ‘There’s ANPR in the university car park!’ he said excitedly.