Conway kept ignoring him. Said to Holly, ‘You’re the one who knew the phone needed to disappear. None of the others: just you. And the killer had been deleting the meeting texts as she went; you’d never have known they existed, unless you were the one who sent them.’

Mackey said, ‘Or unless someone told her, or unless she guessed, or unless she overreacted to what she already knew – God forbid a teenage girl should overreact, am I right?’

Conway looked at him then. Said, ‘I’m done interviewing you. You answer one more question, we’re getting a different appropriate adult.’

Mackey thought her over. Glint in his eye, raking her, would’ve had me twitching; Conway didn’t notice or didn’t care. Just waited for him to finish up and answer her.

‘Seems to me,’ he said, and stood up, ‘that you and I both need a moment to clear our heads. I’m going out for a smoke. I think you should join me.’

‘I don’t smoke.’

‘I’m not looking for a chance to give you shite about your attitude, Detective. That I could do right here. I’m suggesting that a deep breath and a bit of fresh air might do us both good; get us back on the right foot. When we come back, I promise not to answer any more questions for Holly. How’s that?’

I moved. This was it; I couldn’t tell what or how, but I could feel it, yelling warnings. Conway glanced at me; I thought Careful, loud as I could. She glanced at Mackey’s smile – open, straightforward, just the right bit sheepish.

Said, ‘Smoke fast.’

‘You’re the boss.’

I followed them to the doorway. When Mackey arched an eyebrow at me, I said, ‘I’ll wait out here.’

His grin said Good boy, you protect yourself from the scary little girl. I didn’t bite. He matched Conway’s pace down the corridor, so their steps fading away sounded like one person’s. Shoulder to shoulder, they looked like partners.

Holly hadn’t watched them go. Every muscle of her was still clamped tight; there was a ferocious crease between her eyebrows. She said, ‘Do you honest to God think I killed Chris?’

I stayed in the doorway. ‘What would you think, if you were me?’

‘I hope I’d be good enough at my job that I could tell when someone’s not a murderer. Jesus.’

Her adrenaline was firing, touch her and the electric zap would’ve kicked you across the room. I said, ‘You’re hiding something. That’s all I know. I’m not good enough to telepathically guess what it is. You need to tell us.’