‘Don’t be daft.’ She pauses. ‘I’d rather not be on my own right now.’

Bex doesn’t sound like herself at all. She’s usually so ballsy. Jake pushes open the sitting room door. The sofa isn’t the biggest.

‘Kate told me about Facebook,’ she continues, changing tack again. ‘The double on the beach in Thailand called Gil.’

Jake braces himself for another tirade, but Bex isn’t angry with him for hacking into Kate’s account. Far from it.

‘I really don’t know what she’s got herself into,’ she continues.

‘With Rob?’ he asks, surprised. ‘I thought you approved.’

‘I did. Still do. But… It sounded right weird, that man threatening to come back and take over Rob’s life. What sort of a knob would say a thing like that? Makes me wonder if Kate might be onto something.’ She pauses. ‘If she hasn’t got Capgras.’

‘If it’s not Capgras, it’s something else in her head,’ Jake says, for his own benefit as much as hers. ‘Rob hasn’t been replaced by a double. That sort of thing just doesn’t happen. You and I know that.’

He leans forward and glances at the Google results for Kirby, Rob’s Facebook friend. He’s been searching all evening, ever since he left DI Hart in the water meadow. Was it wrong to accuse the detective’s son of arson? There’s no proof. He looks at the screen again. He hasn’t been able to find anyone who fits Kirby’s Facebook profile. Odd. No one even close to a match.

‘You’re right,’ Bex says. ‘I saw Rob on Paddington station and I’ve talked to him on FaceTime down here. It’s ridiculous, the whole idea.’

She still doesn’t sound sure. ‘So what’s the problem?’ Jake asks.

She hesitates before speaking.

‘The Thailand story’s changed things, that’s all. Got me thinking. What if there really are two of them? The one I saw in London and the one Kate met down in Cornwall? Rob and this bloke Gil?’

‘It’s easy to get carried away,’ Jake says, trying not to sound patronising. Too many years in journalism have left him with a default cynicism that he’s not proud of, but it prevents him from leaping to fanciful conclusions.

He lets Bex talk some more. She has a lot to get off her chest, including a couple of jets they heard during a FaceTime chat that apparently proved Rob was still in Cornwall. It’s clear to him that things have got out of hand for Bex and Kate in their seaside bubble.

‘I was going to call Kate after she’s seen this Dr Varma,’ he says, typing in some new search terms for the elusive Kirby. ‘But maybe it’s best if you do it.’