Daniel nodded, without looking up. Abby ran upstairs, light in her sock feet; I heard her opening and closing drawers and, after a minute, starting to sing to herself again. “I leaned my back up against an oak, I thought it was a trusty tree…”

Lexie smoked more than I did, a pack a day, and she started after breakfast. I took Daniel’s matches and lit up.

Daniel checked the page of his book, closed it and put it aside. “Should you really be smoking?” he asked. “Under the circumstances.”

“No,” I said pertly, and blew a stream of smoke across the table at him. “Should you?”

That made him smile. “You’re looking better this morning,” he said. “Last night you seemed very tired; a little lost, somehow. Which I suppose is only to be expected, but it’s nice to see your energy starting to come back.”

I made a mental note to up the boing level, gradually, over the next few days. “In the hospital they kept saying it would take a while and not to rush myself,” I said, “but they can stick it in their ear. I’m bored of being sick.”

The smile deepened. “Well, so I imagine. I’m sure you were a dream patient.” He leaned over to the cooker, tilted the coffeepot to see if there was anything left. “How much of the incident itself do you actually remember?”

He was pouring himself the last of the coffee and watching me; his face was serene, interested, untroubled. “Bugger-all,” I said. “That whole day’s gone, and bits from before. I thought the cops told you.”

“They did,” Daniel said, “but that didn’t mean it was necessarily the case. You could have had your own reasons for telling them that.”

I looked blank. “Like what?”

“I have no idea,” Daniel said, replacing the coffeepot carefully on the stove. “I hope, though, that if you do remember anything and you’re unsure whether to take it to the police, you won’t feel you have to deal with it alone; you’ll come and talk to me, or to Abby. Would you do that?”

He sipped his coffee, one ankle crossed neatly over the opposite knee, watching me calmly. I was starting to see what Frank meant about these four giving away very little. This guy’s expression would have worked equally well whether he had just come from choir practice or from ax-murdering a dozen orphans. “Well, yeah, sure,” I said. “But all I remember is coming home from college on the Tuesday evening and then getting really, really sick in a bedpan, and I already told the police all that.”

“Hmm,” said Daniel. He pushed the ashtray over to my side of the table. “Memory is an odd thing. Let me ask you this: if you were to-” But just then Abby came clattering back down the stairs, still singing, and he shook his head and stood up and started patting at his pockets.

I waved from the top of the steps while Daniel pulled out of the driveway in a fast expert arc, and the car disappeared among the cherry trees. When I was sure they were gone, I shut the door and stood still in the hallway, listening to the empty house. I could feel it settling, a long whisper like shifting sand, to see what I would do now.

I sat down at the bottom of the stairs. The stair carpet had been taken off, but they hadn’t got around to doing anything instead; there was a wide unvarnished band across each step, dusty and worn down in the middle by generations of feet. I leaned against the newel post, wriggled till I got my back comfortable, and thought about that diary.

If it had been in Lexie’s room, the Bureau gang would have found it. That left the rest of the house, the whole garden, and the question of what was in there that she had wanted to hide even from her best friends. For a second I heard Frank’s voice, in the squad room: her friends close and her secrets closer.

The other possibility was that Lexie had kept it on her, that she had had it in a pocket when she died and the killer had nicked it. That would explain why he had taken the time and the risk to go after her (pulling her into cover, black darkness and his hands moving fast over her limp body, patting down pockets, glazed with rain and blood): if he needed that diary.

That fit with what I knew about Lexie-keep secrets close-but, on a more practical level, it would have had to be pretty small to go into a pocket, and she would have had to swap it over every time she changed clothes. Finding a hiding place would have been simpler and safer. Somewhere it would be safe from rain and from accidental discovery; somewhere she could be sure of privacy, even living with four people; somewhere she could go whenever she wanted, without catching anyone’s attention; not her room.

There was a toilet on the ground floor and a full bathroom on the first. I checked the jacks first, but the room was the size of a coat closet, and once I’d looked in the cistern I had basically exhausted the possibilities. The main bathroom was big: 1930s tiles with a black-and-white checked border, chipped bath, unfrosted windows with tattered net curtains. The door bolted.

Nothing in the cistern, or behind it. I sat down on the floor and pulled out the wooden panel from the side of the bath. It came easily; a scraping sound, but nothing that running water or a flush wouldn’t cover. Underneath there were cobwebs, mouse droppings, sweeps of finger marks in the dust; and, tucked in a corner, a tiny red notebook.

My breath felt like I’d been running. I didn’t like this; didn’t like how, with acres to choose from, I had come homing straight to Lexie’s hiding place as if I had no choice. Around me the house seemed to have tightened and drawn closer, leaning in over my shoulder; watching; focused.

I went up to my room-Lexie’s room-and found my gloves and a nail file. Then I sat back down on the bathroom floor and carefully, holding it by the edges, pulled out the notebook. I used the file to turn the pages. Sooner or later, the Bureau would need to fingerprint this.

I had been hoping for a pour-your-heart-out diary, but I should have known better. This was just a date book, red fake-leather cover, a page for each day. The first few months were covered with appointments and reminders in that quick, rounded writing: Lettuce, Brie, garlic salt; 11 tut Rm 3017; elec bill; ask D Ovid book?? Homey, innocuous stuff, and reading it made me edgier than anything yet. When you’re a detective you get used to invading people’s privacy in every way you can think of, I had slept in Lexie’s bed and I was wearing her clothes, but this; this was the small day-to-day debris of her life, it had been only for herself, and I had no right to it.

In the last few days of March, though, something changed. The shopping lists and tutorial timetables vanished and the pages went bare. There were only three notes, in a hard, dashed-off scribble. The last of March: 10.30 N. The fifth of April: 11.30 N. And the eleventh, two days before she died: 11 N.

No N in January or February; no mention till that appointment on the last of March. The list of Lexie’s KAs wasn’t a long one, and as far as I could remember, no one on it began with N. A nickname? A place? A café? Someone from her old life, just like Frank had said, resurfacing from nowhere and wiping the rest of her world blank?

Across the last two days of April was a list of letters and numbers, in that same furious scrawl. AMS 79, LHR 34, EDI 49, CDG 59, ALC 104. Scores from some game, sums of money she’d lent or borrowed? Abby’s initials were AMS-Abigail Marie Stone-but the others didn’t match anyone on the KA list. I stared at them for a long time, but the only thing they reminded me of was the plate numbers on classic cars, and I couldn’t for the life of me think of a reason why Lexie would be car spotting or why, if she was, it would be a state secret.

Nobody had said one word about her acting tense or odd, her last few weeks. She seemed fine, every single interviewee had told Frank and Sam; she seemed happy; she seemed just like always. The last video clip was from three days before she died and it showed her clambering down a ladder from the attic, a red bandanna tied round her hair and every inch of her powdered gray with dust, sneezing and laughing and holding out something in her free hand: “No, look, Rafe, look! It’s”-explosive sneeze-“it’s opera glasses, I think they’re mother-of-pearl, aren’t they brilliant?” Whatever had been going on, she had hidden it well; too well.