“As you can see,” I said, “we had a little disagreement. You might want to get him checked out for concussion. I’ve documented this for future reference, if you need pictures.”

Stephen was looking Shay over carefully, from head to toe, not missing an inch. “I might, yeah. Thanks. Do you want those back straight away? I can put him in mine.”

He was pointing at my handcuffs. I said, “I’m not planning on arresting anyone else tonight. Get them to me some other time. He’s all yours, Detective. He hasn’t been cautioned yet; I left that for you. You don’t want to get sloppy on the technicalities, by the way. He’s smarter than he looks.”

Stephen said, trying to phrase it delicately, “What do we . . . ? I mean . . . you know. Reasonable cause for arrest without a warrant.”

“I figure this story will probably have a happier ending if I don’t spill all our evidence in front of the suspect. But trust me, Detective, this isn’t just sibling rivalry gone wild. I’ll give you a ring in an hour or so for a full briefing. Until then, this should keep you going: half an hour ago he gave me a full confession to both murders, complete with in-depth motives and details about the manner of death that only the killer could know. He’s going to deny it till the cows come home, but luckily I’ve got lots of other tasty nibbles stashed away for you; that’s just your starter. Think it’ll hold you for now?”

Stephen’s face said he had his doubts about that confession, but he also had better sense than to go there. “That’s plenty. Thanks, Detective.”

Downstairs, Ma yelled, “Seamus! Francis! If this dinner burns on me, I swear I’ll malavogue the pair of yous!”

I said, “I’ve got to split. Do me a favor: hang on here for a while. My kid’s downstairs, and I’d rather she didn’t see this. Give me time to get her out before you leave. OK?”

I was talking to both of them. Shay nodded, without looking at either one of us.

Stephen said, “No problem. Will we get comfortable, yeah?” He tilted his head towards the sofa and reached out a hand to haul Shay to his feet. After a second, Shay took it.

I said, “Good luck.” I zipped up my jacket over the blood on my shirt, and swiped a black baseball cap—“M. Conaghy Bicycles”—off a coat hook to cover the cut on my head. Then I left them there.