Conway shut the book. Delicate touch, when she needed it. ‘You should’ve seen this place, after the murder. The kids didn’t get left on their own for a second, in case Hannibal Lecter jumped out of a wardrobe and ate their brains. None of them would go to the jacks without five of their mates in tow. Our lot everywhere, teachers patrolling the corridors, nuns flapping about, everyone going off like fire alarms if they spotted anything out of the ordinary. This’ – she flicked a finger at the book, no touching – ‘would’ve been the smart thing to do: leave the key, don’t risk getting caught moving it. And just a few weeks later, the school year finished up. When our girls came back in September, they were fourth-years. No code for this room, no good reason to be in it. Coming after the key would’ve been riskier than leaving it. How often do you think this book gets read? What’s the odds of anyone finding the key, or knowing what it was if they did?’

‘If Joanne or whoever didn’t bin the key, it’s a good bet she didn’t wipe down the book.’

‘Nah. We’ll get prints.’ Conway pulled a plastic evidence bag out of her satchel, shook it open with a snap. ‘Who d’you figure for the text? None of Holly’s lot are mad about Joanne.’

She held the bag open while I balanced the book into it, two-fingered. I said, ‘“Who” isn’t the bit that’s getting me. I’d love to know why.’

Wry glance from Conway, as she tucked the bag back into her satchel. ‘My scare speech wasn’t good enough for you?’

‘It was good. But it wouldn’t scare anyone into texting us about this. What’s to be scared of? Why would the killer come after her for knowing this key was here?’

‘Unless,’ Conway said. She was pulling off her gloves, carefully, finger by finger. ‘Unless the killer’s Joanne.’

The first time we’d had a name to say. It sent a fine zing through the air, rippling the throws on the sofas, twitching the curtains.

I said, ‘You’re the boss. But if it was me, I wouldn’t go at her yet.’

I half-expected a slap-down. Didn’t get one. ‘Me neither. If Joanne hid this, her buddies knew about it. Who d’you want to try? Alison?’

‘I’d go for Orla. Alison’s nervier, all right, but that’s not what we need. One push and she’ll run crying to Daddy, and we’re bollixed.’ The we flicked Conway’s eyebrow, but she said nothing. ‘Orla’s more solid, and she’s thick enough that we can run rings round her. I’d try her.’

‘Mm,’ Conway said. She was opening her mouth to say something else when we heard the sound.