My second thought: the Spains had had an alarm system. The panel was a fancy modern one, discreetly tucked away behind the door. The OFF light was a steady yellow.

Then I saw the hole in the wall. Someone had moved the phone table in front of it, but it was big enough that a jagged half-moon still poked out. That was when I felt it: that needle-fine vibration, starting in my temples and moving down the bones into my eardrums. Some detectives feel it in the backs of their necks, some get it in the hair on their arms—I know one poor sap who gets it in the bladder, which can be inconvenient—but all the good ones feel it somewhere. It gets me in the skull bones. Call it what you want—social deviance, psychological disturbance, the animal within, evil if you believe in that: it’s the thing we spend our lives chasing. All the training in the world won’t give you that warning when it comes close. You get it or you don’t.

I took a quick look at Richie: grimacing and licking his lips, like an animal that’s tasted something putrid. He got it in his mouth, which he would need to learn to hide, but at least he got it.

Off to our left was a half-open door: sitting room. Straight ahead, the stairs and the kitchen.

Someone had put time into doing up the sitting room. Brown leather sofas, sleek chrome-and-glass coffee table, one wall painted butter yellow for one of those reasons that only women and interior designers understand. For the lived-in look, there was a good big telly, a Wii, a scattering of glossy gadgets, a little shelf for paperbacks and another one for DVDs and games, candles and blond photos on the mantelpiece of the gas fire. It should have felt welcoming, but damp had buckled the flooring and blotched a wall, and the low ceiling and the just-wrong proportions were stubborn. They outweighed all that loving care and turned the room cramped and dim, a place where no one could feel comfortable for long.

Curtains almost drawn, just the crack that the uniforms had looked through. Standing lamps on. Whatever had happened, it had happened at night, or someone wanted me to think it had.

Above the gas fire was another hole in the wall, about the size of a dinner plate. There was a bigger one by the sofa. Pipes and straggling wires half showed from the dark inside.

Beside me Richie was trying to keep the fidgeting down to a minimum, but I could feel one knee jiggling. He wanted the bad moments over and done with. I said, “Kitchen.”

It was hard to believe that the same guy who had designed the sitting room had come up with this. It was a kitchen-cum-dining-room-cum-playroom, running the whole length of the back of the house, and it was mostly made of glass. Outside the day was still gray, but the light in that room was full and dazzling enough to make you blink, with a lift and a clarity that told you the sea was very near. I’ve never been able to see why it’s supposed to be a plus if your neighbors can check out what you’re having for breakfast—give me net-curtain privacy any day, trendy or not—but that light almost made me understand.