McCann still does. For some reason that’s the thing that sends a cold spike down my spine. That’s the moment when it goes right through me: that guy is the same McCann who was waiting for me outside the Murder building yesterday morning, all stubble and restlessness. That missing-persons case followed him from the dim house with the silent kid listening, down every twisting road, all the way to our bright shouting squad room. That’s the moment when I understand that McCann is our man.

‘She remembered he was married, with two little boys – her mum asked him over and over, “And you wouldn’t leave them, would you? You’d never walk away from your own wife and your own children?” and he always said no, he never would. She remembered his coat, this grey tweed overcoat – he’d leave it hanging on the banister, and she’d pick bits of fluff off it while she listened and stick them in his pockets – she didn’t like him being there. But the big thing Ash remembered, the thing she wrote down with circles and stars all round it, was that he was into her mum.’

‘Into her like what?’ I ask. ‘Like they had a relationship? Like he came on to her?’

‘Jesus, no!’ The instant squeeze of disgust on Lucy’s face says it’s true. ‘This wasn’t some Greek tragedy; Ash wasn’t shagging her mum’s ex. Just, in hindsight, she was pretty much positive that he’d fancied her mum. She figured that was why he spent so much time on the case. Even though he was married with kids, even though he was supposed to be professional, even though Ash’s mum was going nuts trying to find her husband: he fancied her, and he went with it.’

‘And Aislinn thought that was important.’

‘Yeah. She knew she could use it. She said, “If he’s that kind of guy, the guy who does stupid stuff for pretty women, I can be that. I’d have to change my look anyway; I can’t have him recognising me and getting suspicious – not that he ever looked twice at me, he barely noticed I existed, but I’ll only get one chance at this and I’m going to do it right.” And she did.’