“Or else,” Richie said, “it could be the other way round.” His eyes had slipped away from me again, back to the chaos. “The adults were the main target, or one of them was, and the bloody mess was the plan all along; that’s what he was after. The kids were just something he had to get rid of, so they wouldn’t wake up and get in the way of the good stuff.”

Larry had delicately worked one finger under his hood and was scratching where his hairline should have been. He was getting bored—all the psychological chitchat. “Wherever he started, I’d say he finished up by leaving through the back door, not the front. The hall is clean, so’s the drive, but we found three blood smears on the paving stones in the back garden.” He beckoned us towards the window and pointed: neat strips of yellow tape, one just outside the door, two by the edge of the grass. “The surface is uneven, so we’re not going to be able to tell you what kind of smears—they could be shoe prints, or transfer where someone dropped a bloody object, or they could be droplets that got smudged somehow, like if he was bleeding and then stepped on the blood. One of the kids could have scraped its knee days ago, for all we know at this stage. All we’re saying is, there they are.”

I said, “So he’s got a back door key.”

“That or a teleporter. And we found one other thing in the garden that I thought you might want to know about. What with the trap in the attic and all.”

Larry wiggled his fingers at one of his boys, who picked an evidence bag off a pile and held it out. “If you’re not interested,” he said, “we’ll just bin it. Disgusting object.”

It was a robin, or most of one. Something had taken its head off, a couple of days back. There were pale things curling in the ragged dark hole.

“We’re interested,” I said. “Any way you can work out what killed it?”

“Really and truly not my area, but one of the boys back at the lab does outdoorsy things at weekends. Tracks badgers in his moccasins, or whatever. I’ll see what he says.”

Richie was leaning in for a closer look at the robin: tiny clenched claws, crumbs of earth hanging from the bright breast feathers. It was starting to stink, but he didn’t seem to notice. He said, “Most things, if they killed it they’d eat it. Cats, foxes, anything like that: they’d have had the guts out of it. They don’t kill for the sake of it.”

“I wouldn’t have taken you for the woodsman type,” Larry said, arching an eyebrow.

Richie shrugged. “I’m not. I was posted down the country for a while, in Galway. Picked bits up from listening to the local lads.”

“Go on, then, Crocodile Dundee. What would take the head off a robin and leave the rest?”