‘Silver-grey hair and she’s only forty? Still, they say people with very dark hair go grey youngest.’ Charlie Zailer drums her fingers on the table, raises an eyebrow at me. ‘So, you’ve seen her, then? If you know what kind of hair she’s got, you must have seen her, even if you don’t know her personally.’

I say nothing.

‘Or perhaps you’ve seen a picture of her? No, I think you’ve seen her in the flesh. A picture wouldn’t have put your mind at rest. Aidan told you he’d killed her, and you needed to see her in person, see for yourself that she was still alive. Undeterred by the sheer unlikeliness of anyone pretending they’ve killed someone when they haven’t, you set out to find this dead woman and, lo and behold, she wasn’t dead at all. Is that how it happened?’

The silence between us is unbearable. I try to pretend she isn’t here, that I’m alone in the room.

‘Curiouser and curiouser,’ she mutters. ‘Okay, here’s a question you might be happier about answering: what are you doing here, apart from wasting my time?’

‘What?’

‘Why are you here? Aidan hasn’t killed anyone—fine. Mary Trelease is alive—hooray. What do you want from me, exactly?’

Now I can talk freely. ‘I want you to check that what I’m saying is true. If it is, you could . . . convince Aidan. I’ve tried and failed. You’re the police—he’d listen to you.’

‘If it’s true? So you’re not a hundred per cent sure Aidan didn’t kill this woman who’s alive. Make up your mind.’

‘I’m as sure as I can be, but . . . what if the woman I think is Mary Trelease isn’t? What if . . . I know it sounds insane, but what if she’s some other woman who fits Mary’s description, a relative or . . . or . . .’ Or someone pretending. I don’t say it; it would make me sound paranoid. ‘There are things the police can find out that I can’t.’

Charlie Zailer sighs. ‘The police find things out in the process of investigating crimes. Nothing’s happened here, according to you. There’s no crime to investigate. Correct?’ She opens and closes her lips several times, making a popping noise. She appears to be thinking. Perhaps she’s bored, daydreaming. After a few seconds, she says, ‘From my point of view, there are three questions. One: did Aidan kill the woman you’re talking about, the person you know as Mary Trelease?’

‘He didn’t. He can’t have. She’s alive.’

‘All right. Then did he kill another person called or known by the name of Mary Trelease? And lastly, question number three: did he kill or injure anyone? Is there a body somewhere, waiting to be found? Not that it’ll still be a body by now, if the killing happened years ago.’

‘Aidan couldn’t hurt anybody. I know him.’

She puffs her cheeks full of air, then blows it out in one breath. ‘If you’re right, you should be consulting a shrink, not me.’