“I mean the gathering of the suspects before the great detective—Poirot, Marple, in this case me—reveals the guilty party, or parties.”

“Someone steal the diamonds again?” They weren’t on the mantelpiece. I threw a quick glance at the rug in front of the fire.

“No, we’ve got a new mystery. I’m calling it the bodies in the library.”

With that, I knew what he was getting at and experienced a wave of horror, so like desire when you come to think of it, in the way it gripped you, made you feel like your organs were melting.

I poured out a coffee, the pot chattering against the rim of the cup. “Pete, where are Em and Marcus? We should get going.”

“Marcus went to look for her.” Peter was still picking out the little tune.

“Can you stop that? It’s driving me nuts.” His hands froze and then he set them down gently in his lap.

“Thing is, Andy,” Rob went on, “yours truly passed out last night on the couch in the library. Not that you’d have known that, because you went up so early. Dave too, when I think about it. Anyway, so there was I passed out on the couch and then about one, maybe two, I wake up. It’s pitch-black so I can’t see anything, but I’m hearing these noises. Can you guess what it was? No? Don’t want to take a guess, a wild stab in the dark?”

I heard the front door slam.

“Why don’t you shut your fucking mouth?”

“Rob, what are you talking about?” Alice had gotten to her feet.

For a moment, the impish mask slipped and Rob looked almost sad. “Sorry, sis,” he said. “But better you find out now than later. Better you know him for what he is.”

David still didn’t say anything. His eyes followed Rob. He didn’t even look particularly surprised.

Turning back to me, Rob went on. “It was a couple, Andy. Two people. Fucking. At it. Hammer and tongs. On my parents’ best Persian rug. Sixteen bedrooms to choose from—”

Marcus came in. He had his boots on and they were caked in snow.

“Shut up, Rob. Just shut up!” And I made a move toward him like I was going to cover his mouth with my hands and stop the words from coming out.

“Just in time, Marcus. We’re reaching the denouement! I’m about to reveal … where’s Em? She should be here for this too really. I’m just about to tell you how I caught Andy and David fucking last night.”