‘I don’t know. He went out on Saturday evening and he hasn’t come back. He’s not answering his phone.’

‘Have you checked the hospitals?’

‘Yes, and I’ve reported it to the police, but they think he’ll be back. According to their checklist, he’s just left. Look, I wouldn’t ask you this—’

I stop dead. I should have thought this through. If I tell her, then she’s going to take herself off the app. I want to keep her there, trapped on my screen, where I can keep an eye on her.

‘You wouldn’t ask me what?’

I’m thinking on my feet, but luckily that is one of my skills. ‘When he came back from his trip to the shops on Thursday evening he said he’d met a mum from the school and that they’d had a conversation. From the way he described her, it sounded like you. It’s a long shot, but he was a little taciturn afterwards, and I thought it might have had something to do with what’s happened now.’

She raises her eyebrows. ‘And what did he talk to this mystery woman about?’

‘I don’t know. I didn’t get that far.’ I rub my eyes and yawn. ‘I was distracted.’

‘Well, I haven’t got a clue. I’m not even sure I’d recognize your husband. You haven’t introduced us.’

‘We’re not married. You must have met him.’

‘Nope.’ Her smile is quick to arrive and quicker to depart; a sharp tightening of the muscles at the corners. ‘It’s tough being an attractive single mother. Other women feel threatened.’

‘I’m not … I don’t …’

‘Oh, I’m not accusing you in particular. It’s just a general thing, a feeling I get when I walk into a room. If I’m invited to a party I have to be careful not to let myself be monopolized by any of the husbands. I can feel their wives twitching, you know, and I can tell when they’re about to wander over, slide their arm through his, kiss his cheek, and draw him away.’ She puts on a mimsy voice. ‘“Oh darling, you must meet so-and-so.” It’s a whole production.’

It’s so believable. How would I feel if Nick spent too long talking to Anna? Not great, frankly. I might find the way she plays with her hair irritating, but I don’t think Nick would. One hundred per cent I would go up and put my arm round him.

‘I don’t want their bloody husbands anyway. God. I can’t think of anything worse.’

‘What happened to Kai’s dad, if you don’t mind me asking?’

‘Prostate cancer,’ she says. ‘Three months from diagnosis to death. I barely had a chance to get used to the idea before he was gone. I was widowed at twenty-eight.’