He tipped up the glass to get the last drops and reached for his jacket. “Been fun catching up, babe. You have my mobile number. Let me know what you decide about tomorrow night.”

And he let himself out. It was only as the door shut behind him that I realized what I had slipped into asking: What about college, any boyfriend? as if I were checking the plan for holes; as if I were thinking about doing it.

Frank’s always had a knack for knowing exactly when to leave it. After he’d gone, I sat on the windowsill for a long time, staring out over the rooftops without seeing them. It was only when I got up for another glass of wine that I realized he had left something on my coffee table.

It was the photo of Lexie and her mates in front of Whitethorn House. I stood there, with the wine bottle in one hand and my glass in the other, and thought about turning it face down and leaving it there till Frank gave up and came back for it; thought, for a minute, about sticking it in an ashtray and burning it. Then I picked it up and brought it back to the windowsill with me.

She could have been any age. She had been passing for twenty-six, but I would have believed nineteen, or thirty. There wasn’t a mark on her face, not a line or a scar or a chicken-pox blemish. Whatever life had thrown at her before Lexie Madison fell into her lap, it had rolled over her and burned off like mist, left her untouched and pristine, sealed without a crack. I looked older than her: Operation Vestal gave me my first lines around my eyes, and shadows that don’t go away with a good night’s sleep. I could practically hear Frank: You lost a shitload of blood and you’ve been in a coma for days, the eye bags are perfect, don’t go using night cream.

At her shoulders the housemates watched me, poised and smiling, long dark coats billowing and Rafe’s scarf a flash of crimson. The angle of the shot was a little off-kilter; they had propped the camera on something, used a timer. There was no photographer on the other side telling them to say cheese. Those smiles were private things, just for one another, for their someday selves looking back, for me.

And behind them, almost filling the shot, Whitethorn House. It was a simple house: a wide gray Georgian, three stories, with the sash windows getting smaller as they went up, to give the illusion of even more height. The door was deep blue, paint peeling away in big patches; a flight of stone steps led up to it on either side. Three neat rows of chimney pots, thick drifts of ivy sweeping up the walls almost to the roof. The door had fluted columns and a peacock’s-tail fanlight, but apart from that there was no decoration; just the house.

This country’s passion for property is built into the blood, a current as huge and primal as desire. Centuries of being turned out on the roadside at a landlord’s whim, helpless, teach your bones that everything in life hangs on owning your home. This is why house prices are what they are: property developers know they can charge half a million for a one-bedroom dive, if they band together and make sure there’s no other choice the Irish will sell a kidney, work hundred-hour weeks and pay it. Somehow-maybe it’s the French blood-that gene missed me. The thought of a mortgage round my neck makes me edgy. I like the fact that my flat is rented, four weeks’ notice and a couple of bin liners and I could be gone any time I choose.

If I had ever wanted a house, though, it would have been a lot like this one. This had nothing in common with the characterless pseudohouses all my friends were buying, shrunken middle-of-nowhere shoeboxes that come with great spurts of sticky euphemisms (“architect-designed bijou residence in brand-new luxury community”) and sell for twenty times your income and are built to last just till the developer can get them off his hands. This was the real thing, one serious do-not-fuck-with-me house with the strength and pride and grace to outlast everyone who saw it. Tiny swirling flecks of snow blurred the ivy and hung in the dark windows, and the silence of it was so huge that I felt like I could put my hand straight through the glossy surface of the photo and down into its cool depths.

I could find out who this girl was and what had happened to her without ever going in there. Sam would tell me when they got an ID or a suspect; probably he would even let me watch the interrogation. But right at the bottom of me I knew that was all he would ever get, her name and her killer, and I would be left to wonder about everything else for the rest of my life. That house shimmered in my mind like some fairy fort that appeared for one day in a lifetime, tantalizing and charged, with those four cool figures for guardians and inside secrets too hazy to be named. My face was the one pass that would unbar the door. Whitethorn House was ready and waiting to whisk itself away to nothing, the instant I said no.

I realized the photo was about three inches from my nose; I had been sitting there long enough that it was getting dark, the owls doing their warm-up exercises above the ceiling. I finished off the wine and watched the sea turn thunder-colored, the blink of the lighthouse far off on the horizon. When I figured I was drunk enough not to care if he gloated, I texted Frank: What time is that meeting?

My phone beeped about ten seconds later: 7 sharp, see you there. He had had his mobile ready to hand, waiting for me to say yes.

That evening Sam and I had our first fight. This was probably overdue, given that we had been going out for three months without even a mild disagreement, but the timing sucked all round.

Sam and I got together a few months after I left Murder. I’m not sure exactly how that happened. I don’t remember a whole lot about that period; I appear to have bought a couple of truly depressing sweaters, the kind you only wear when all you really want is to curl up under the bed for several years, which occasionally made me wonder about the wisdom of any relationship I had acquired around the same time. Sam and I had got close on Operation Vestal, stayed that way after the walls came tumbling down-the nightmare cases do that to you, that or the opposite-and long before the case ended I had decided he was pure gold, but a relationship, with anyone, was the last thing I had in mind.

He got to my place around nine. “Hi, you,” he said, giving me a kiss and a full-on hug. His cheek was cold from the wind outside. “Something smells good.”

The flat smelled of tomatoes and garlic and herbs. I had a complicated sauce simmering and water boiling and a huge packet of ravioli at the ready, going by the same principle women have followed since the dawn of time: if you have something to tell him that he doesn’t want to hear, make sure there is food. “I’m being domesticated,” I told him. “I cleaned and everything. Hi, honey, how was your day?”

“Ah, sure,” Sam said vaguely. “We’ll get there in the end.” As he pulled off his coat, his eyes went to the coffee table: wine bottles, corks, glasses. “Have you been seeing fancy men behind my back?”

“Frank,” I said. “Not very fancy.”

The laughter went out of Sam’s face. “Oh,” he said. “What did he want?”

I had been hoping to save this for after dinner. For a detective, my crime-scene cleanup skills suck. “He wanted me to come to your case meeting tomorrow night,” I said, as casually as I could, heading over to the kitchenette to check the garlic bread. “He went at it sideways, but that’s what he was after.”

Slowly Sam folded his coat, draped it over the back of the sofa. “What did you say?”

“I thought about it a lot,” I said. “I want to go.”

“He’d no right,” Sam said, quietly. A red flush was starting high on his cheekbones. “Coming here behind my back, putting pressure on you when I wasn’t there to-”