‘You coming?’ she asks Bex, who is sitting with Stretch on the sofa.

  ‘Sure,’ Bex says, more subdued than usual. Presumably from their afternoon gin session. Kate’s hungover too. And still in shock.

  They’ve talked long and hard about the sound of the military jets. As soon as she looked at his face and heard them on the speakers, she cut off the FaceTime call, snapping shut the laptop. She also turned off her phone again and persuaded Bex to do the same. The landline was still disconnected after Rob’s earlier call.

  Neither of them can be certain of what it means. Either Rob is back down here without telling her. Or it wasn’t Rob on the screen, it was his double, who is now in Cornwall. It didn’t look like Rob, but Bex is certain that it was him. Perhaps Kate was imagining the jets, the guilty look in his eyes?

  She hopes so. She will ring him later from the beach. No facetiming, just a normal call. She can’t keep contacting him and hanging up. He’s used to the poor communications down here, but he’ll still be worrying what happened, trying to contact her.

  *

  There’s a good crowd on Pendower beach tonight, about twenty of them, thanks to Rob. Kate’s always urging him to do more for the environment. He’s keen, just needs reminding, like buying an electric car rather than a diesel-guzzling 4x4. For the past few months, his tech company has sponsored the local beach cleans, which means it pays for their T-shirts and for fuel for the community van that brought them over here. She’s trying to persuade Rob to cough up for an electric minibus. Most importantly, the sponsorship includes putting money behind the pub bar afterwards for all the volunteers.

  ‘They’ve got jets in London too,’ Bex says as they start to work their way down the high-tide mark. She doesn’t sound convinced and Kate doesn’t reply.

  Stretch is sniffing about in front of them. It’s a falling tide, the best time for a clean. Behind them, a few families are still enjoying the last of the sun as it sets over St Mawes in the distance. It’s been one of those cloudless Cornish days that no one wants to end, the summer heat still lingering in the sand and on glowing, sunburnt cheeks.

  ‘You saw the look on his face though,’ Kate says. ‘He’d been found out.’ She has to believe that Rob would never come down to Cornwall without telling her, which means she must confront this man, ask him who he really is, why he’s here. ‘And the time delay,’ she says, picking up a clump of orange fishing line that’s become tangled with seaweed. ‘Two seconds, at most. He wasn’t that far away.’

  She drops a crumpled can of Coke into her bucket, which also sports Rob’s company name, and looks up, staring back towards the village and the surrounding countryside. Is his double really down here somewhere? Watching them? And what has he done with her Rob? The Rob who has taken care of her for the past five months, nurtured and loved her with such tenderness.

  ‘There is another explanation for all this,’ Bex says.

  ‘I told you, he doesn’t have a twin.’

  ‘It’s not that.’ Bex pauses, looking around the beach. ‘Have you heard of something called Capgras syndrome?’

  ‘No, why?’ she asks. It sounds French, like a resort on the Riviera. ‘Should I have done?’

  ‘Jake was telling me about it yesterday. It’s a…’ Bex hesitates. Unusually for her, she seems to be choosing her words carefully. ‘It’s a state of mind, a condition, where someone thinks that the person they love has been replaced by an impostor, a double.’

  ‘A state of mind?’ Kate says. Bex is not being straight with her. It sounds more serious than that. She’s also been chatting with Jake about her, which is unsettling.

  ‘OK, it’s an illness,’ Bex says. ‘A delusion.’

  ‘I’m not deluded, Bex,’ she snaps, walking on ahead, but a part of her wants to know more.

  ‘It only affects you when you see someone with your eyes,’ Bex adds, calling after her. ‘You don’t think they’re a double if you’re chatting on the phone.’

  Kate stops in her tracks, turning to look at Bex. What did she just say? Kate thinks back to her conversations with Rob, how familiar and reassuring he sounds when she calls him on her mobile.

  ‘Really?’ she says.

  Bex nods, smiling sympathetically. ‘It can be caused by lesions in the part of the brain that was damaged in your car crash.’

  ‘OK,’ Kate says, trying to take everything in. ‘I’m sorry, I didn’t mean—’

  ‘It’s fine,’ Bex says, interrupting her. ‘Maybe you should talk to Dr Varma about it. When you see him next. It might be nothing.’

  It doesn’t sound like nothing. A part of her feels better already. A specific syndrome, linked to her injuries, is more reassuring than thinking that she’s gone mad. It would explain the funny feelings she has every time she sees Rob, the normality of their phone conversations.

  It still doesn’t explain the jets though. She can hear one now, far out at sea. Maybe she’s imagining that one too.

  Five minutes later, Kate and Bex have broken away from the main group and are searching the high-tide line in silence, scattering seabirds in front of them as they go. Jake would know their names. Ruddy turnstones, he whispers in her head.

  ‘Where’s Stretch gone?’ Bex asks, looking up.

  ‘He’ll be around somewhere,’ Kate says.

  She never worries about him straying or getting lost. The beach is dog friendly and people look out for each other’s animals. And then she sees him, fifty yards away, where the sand meets a cluster of rocks at the end of the beach. They don’t usually go that far. It’s always damp and empty and often in shade from the cliffs above. A flock of turnstones is pecking nervously at the sand. Behind them Stretch is sniffing at something on the high-tide line, a large bundle of seaweed, partially hidden. He starts to bark.

  ‘There he is,’ Bex says. ‘What’s he found?’

  Kate doesn’t reply. Instead, she starts to walk over to Stretch, a heavy feeling in her stomach as she quickens her pace. Stretch doesn’t normally bark like this.

  ‘What is it, Kate?’ Bex calls behind her, fear growing in her voice. ‘What’s he barking at?’

  She keeps walking, transfixed by the sight of what Stretch has found.

  ‘Come away from there, weenie toes,’ she says quietly, slowing to a standstill when she’s ten feet away. ‘There’s a good boy.’

  She thinks she’s going to be sick.

  ‘Oh my God,’ Bex says, now beside her, hand over her mouth.

  ‘We’d better call the police,’ Kate manages to say.

  44

  Jake

  Jake is back at Bex’s computer screen again. He’s left it long enough, can’t afford to miss the chance to message Kirby. Kirby will be wondering where Kate’s got to.

  He logs into Kate’s account, moving fast. A quick check of the chat window reveals that Rob is offline. He opens up the message thread with Kirby, reminding himself that he’s posting as Kate.

  Sorry, had to pop out. Anything really. Maybe a story from way back, when you were at school together? Travelling? Thailand?

  Has he gone too quickly with the reference to Thailand? Maybe he should have started with something more general, but there’s no saying how long he’s got on here before Rob appears. Or even Bex. He glances at the list of Kate’s friends on the right of the screen, scrolling up and down and up again, watching for a green ‘online’ icon to appear next to Rob’s name.

  Don’t go near what happened to Rob in Thailand.

  He stares at the screen, blood draining from his face. There’s no going back now. He needs to remember exactly what Bex told him, how reticent Rob had been.

  Why not? He briefly mentioned it to me once. How he met his double on a beach. He seemed upset. I want to help him – get him to talk more about it.

  Kirby replies immediately.

  Can I call you?

  Jake starts to panic. Does Kirby have Kate’s mobile number?

  Reception terrible here in Cornwall. Messaging best.

  Again Jake wonders if he’s blown it. Kirby takes a long time – too long – to reply.

  Not sure I should tell you…

  Jake replies instantly, Kate’s words flowing out of him.

  I love Rob. In just a few months, he’s turned my life around.

  And you’ve made him so happy too. He loves you.

  Jake can’t stomach much more of this. Another long pause.

  Give me some time. There’s a lot to tell.

  It’s ten minutes before Kirby returns. Ten minutes in which Jake’s eyes remain glued to the chat window. He scrolls up and down the list again, watching for the green ‘online’ icon to appear next to Rob’s name. For a moment he’s tempted to read some of the previous exchanges between Kate and Rob, but it would be too painful and that’s not what this is about. And then Kirby’s long reply drops in one go. It’s worth the wait.

  We were in Thailand, having a beach party for Robert’s twenty-first birthday. He hasn’t touched drugs for years, as you know. Let’s just say we were young back then. It was late. The stars were shining. And everyone was beautiful – and intoxicated.

  We all wanted a piece of Robert that night and were toasting his birthday and his incredible successes. His first two apps were already sure-fire winners – number ones in the App Store – and he was disrupting markets around the world and making his first million. Ludicrous for someone so young. He was drinking heavily and then popped something strange, we still don’t know what. Next thing I knew, he’d wandered off down the beach into the darkness.

  When he returned, he looked troubled, like death to be honest. He said in a rather rambling speech that he felt he would have to change if he was ever going to make it properly. He joked that all the biggest names in tech, the people he really admired, had not played by the rules to achieve their successes. Failed to pay enough tax, ‘borrowed’ others’ ideas, misused personal data, treated staff badly. The usual stuff. All bullshit, of course, but that’s what he thought, and it bothered him. He was having a moment. Like we all did at that age. Quite an important one in his case. As you know, he’s a major force for good these days, doing all sorts of amazing medical stuff and charity work. So he was kind of conflicted about his achievements to date and how far he could really go in his future career, wrestling with this whole idea of whether you can succeed big time in business and still be a good person.

  Afterwards, I asked him why he’d walked off like that. He fell quiet and said that he thought he’d seen an uninvited guest show up at the party earlier. This guy apparently looked familiar in some weird way and Robert wanted to find him. After searching everywhere he suddenly spotted him at the far end of the beach.

  Jake sits up in his chair.

  And when he caught up with him, Robert got the shock of his life. The man wasn’t just familiar, he looked identical to him. And I mean identical.

  45

  Silas

  Silas glances across at Stonehenge, glowing in the last rays of the evening sun. There could be worse places on the A303 to queue. He was going to take the M5 and M4 to Swindon, but he wants to drop in on Jake, ask him a bit more about his narrowboat insurance. The fire might be an unfortunate coincidence, but the timing still troubles him.

  Strover, sitting beside him, has just taken a call about the number plate that Kate gave them. It still annoys him that Strover offered to run a check on the car in Cornwall without consulting him first, but she’s right, they need Kate onside. According to Strover, the registered keeper of the Tesla is not Rob. It belongs to someone called Gilmour Martin at a ‘care of’ address in London N1. ‘Care of’ addresses are used by the DVLA when the owner of a car is abroad or of no fixed abode. It can be a friend’s house or family member’s. At least, that’s the theory. Criminals try to abuse them too.

  ‘Who’s Gilmour Martin?’ Strover asks.

  ‘He’s not Rob, that’s all we need to know,’ Silas snaps. ‘All Kate needs to know. She can rest easy – her man’s not giving her the runaround. Marriage guidance over. We move on.’

  He’s being irritable, unreasonable. Scratchy, as his Mel used to call it. Has been ever since Conor disappeared. They inch forward in stony silence, two queues of traffic slowly merging into one. And then Strover takes another call. Her digital investigator friend has found a total of seven people whose details match Rob’s facial metrics. No names yet, just images. More details to follow shortly. He’s not sure if Kate will be reassured or horrified.

  ‘Strange thought, isn’t it?’ Silas says, tapping the steering wheel.

  ‘What is?’

  ‘All these other versions of ourselves out there somewhere.’

  Seven people who look like his ex. There’s a thought.

  ‘A bit like Earth,’ Silas continues, warming to his whimsical theme. ‘Must be other planets in the universe just like ours.’

  ‘There’s something you need to know,’ Strover says, in a tone he’s come to recognise. A sure sign that she’s about to fess up to something.

  ‘Go on,’ he says, staring straight ahead. Is she going to tell him that her digital investigator is more than just a friend? It wouldn’t bother him. Each to their own. It might explain why Strover’s romance last year with Sean, the pub conspiracy theorist, didn’t last long.

  ‘Our own custody database, Europol and Interpol resources, they’re all useful, but there are some much bigger databases out there,’ she says tentatively. ‘Legal and illegal ones, on the Dark Web.’

  ‘And your friend accessed them?’

  Strover nods. Silas drives on in silence. Technology has changed policing so much in the past few years, marginalising old-school detectives like him. He might not be much good with computers, but he still needs to understand what they can do.

  ‘Faces scraped from every social media site you’ve ever heard of,’ Strover continues. ‘And from a lot you haven’t. Weibo and Youku in China, VK and Odnoklassniki in Russia. Age-filter apps like FaceApp are also generating huge numbers of faces as everyone shares images of what they’ll look like when they’re ninety.’

  ‘I’d rather not know, thanks,’ Silas says.

  ‘The same’s happening with Zao, the Chinese deepfake app that lets you swap your face for a film star’s. Combine all these uploaded faces with databases used by the world’s law-enforcement and intelligence agencies, and you’ve got a big dataset,’ Strover continues. ‘A lot of mugshots. More than a billion of them.’

  The revenge of the selfie. He’s never understood the urge to ruin a good photo with a gurning face in the foreground.

  ‘How do you search that many faces?’ he asks.

  ‘Clever algorithms, fuzzy logic, probability theory. Russian programmers are leading the way. There’s a search site called SearchFace.ru that can sift through half a billion faces on VK and find a match in seconds. But there’s still a long way to go.’

  Silas thinks back to the last time Strover’s digital investigator friend helped them. And he thought Strover was computer savvy. This woman was extraordinary, blinding him with talk of symmetric-key block ciphers and triple data encryption algorithms. He’d had to look it all up afterwards.

  ‘I’m amazed your friend’s only found seven doubles for Rob.’

  ‘We don’t know exactly who or where they are yet,’ Strover says, reading from her phone. ‘One was last seen in Ireland eight years ago. Two could be in Australia, another possibly in Thailand – the best likeness. The other three were last seen on MySpace and Bebo in North America more than ten years ago.’

  The traffic is beginning to move when another call comes in on the intercom for Silas. It’s the Devon and Cornwall Police Control Room again.

  ‘We’ve located the driver of your car,’ the man says.

  Silas knows at once that it’s bad news. ‘Located’ is never a good word.

  ‘A bunch of beach cleaners discovered his body tonight – about half an hour ago. Pendower, not far from where the car was parked.’

  ‘Suicide?’ Silas asks, wondering if Kate knows.

  ‘We’re launching a murder inquiry. Looks like he’s been shot in the head.’

  46

  Jake

  Jake is desperate to know more about the man at the beach party who looked like Rob, but for some reason Kirby has gone quiet on Facebook. He’s still online but is not responding. Jake prompts him with another message.

  Tell me more?

  And then, after a long wait, Kirby posts another chunk of text online, taking up the story again.

  I never personally saw this guy. Gil, I think his name was. There were hundreds of people on the beach that night – surfers, techies, wannabes who were after a job with Robert. He just told me about him afterwards, said he could have been his twin. Except that Robert doesn’t have a twin and Gil sounded nothing like Robert as a person. Apparently, he was a total loser, a drugs bum.

  Later that evening, he revealed a bit more about what had happened on the beach with Gil, wanted to show me a video on his phone. For a second I thought it was Robert, but then I saw that this guy Gil had a pistol. He was waving it at the camera, gesticulating, making threats – so much anger. Not like Robert at all. He was saying that Robert didn’t have what it took to be really successful. That he was too decent – too damn nice! – and needed to channel his darker impulses. And all the time he’s waving this frickin’ gun around. It was terrifying.

  Rob’s always worried about how we’re all two steps away from being homeless – just like this guy. I think he really got under Rob’s skin, reminded him of how life could be if it all went wrong. Gil was clearly jealous of Rob’s success and his last words were the most chilling. He said he was going to wait until Rob had become a global hotshot. Had a life worth taking. Then he’d come looking for him, wherever he was in the world. Hunt him down. And when he’d found him, he’d… steal his soul.