Hester Nwosu-Kallio kept a lemon cake in her bottom desk drawer for emergencies, and she considered this an emergency.

"Sit," she said. "Both of you. No, Anselm, not in that chair, it has a spring. Take the green one. Dilnoza, here. I cut it thin. If we are going to have a difficult conversation, we shall at least have crumbs."

Her office on the sixth floor was the only room in the Fairhold Building that looked as if someone lived in it. There was a rug, a kettle, a shelf of paperbacks with cracked spines, a photograph of a grey-muzzled spaniel on the windowsill, and a wall of fat three-ring binders, each labelled in a hand like barbed wire. Hester herself was fifty-eight, small, broad-shouldered, in a plum cardigan and sensible flat shoes, with glasses on a chain and iron-coloured hair pinned up with a pencil. She moved like a woman who had been telling large institutions where to put their feet for thirty years. Dilly had hoped to dislike her and failed within ninety seconds.

Sel sat in the green chair and looked at his hands. He had said almost nothing in the lift. He had said, once, "She taught me to ride a bicycle. Not Maurice. Maurice is lying about that. It was Hester," and then closed his mouth, as if the effort of the sentence had cost him a year.

"You are going to ask me about my tablet," said Hester, pouring tea.

Dilly had her whole plan ready: the soft opening, the mention of an audit, the slow circling in. She looked at the plain cardiganed woman and abandoned it.

"Yes. And the ninth key."

"The ninth key is on my chain. It has been on my chain since nineteen ninety-nine, when Odessa gave it to me in a manner suggesting I had won a medal." She lifted a ring from her cardigan pocket and let it swing, brass and iron and one small silver key with a worn bow. "It has not left me. I am not a woman who lends her keys. I am, however, a woman who lends her tablet, and that is my sin."

"Tell me about the tablet."

"I thought so. Junie rang my assistant in a tone, and my assistant is not stupid." Hester sat. She cut a second slice, put it on Sel's knee, and continued to speak in the same dry, unhurried voice, as though reading from a minute. "FDRT-TAB-07. It has not been in my possession since Wednesday at half past four. I did not report it stolen because it was not stolen. I lent it. A member of the Foundation staff asked to borrow it to print the funeral programme. A young man, polite, called Tobin Aldous-Fairweather. He works for Maurice. I did not think twice. I have lent that tablet to every person in this building at one time or another. It is a very ordinary tablet."

"When did you get it back?"

"I have not." She took off her glasses, and without them her face looked suddenly older and softer and much more afraid. "I rang Tobin on Thursday. He said he'd lost it on the train. I said that is not possible, there are no trains in Corliss Ferry after nine. He hung up. I then did the thing I have been trained for thirty years not to do. I did nothing. I sat at this desk and I ate cake and I waited to see who would come."

"We came," said Sel, quietly.

"Yes. I'm glad it was you. I have been thinking, for a week, about what I owe your grandmother." She set the glasses on the blotter, very precisely. "Dilnoza, you have been watching my hands since you sat down."

Dilly had been. She had noted that Hester's left hand lay flat and still while her right poured tea, that her thumb touched her wedding band twice when she said Tobin's name, that she looked at Sel more than at Dilly, and that she had been telling the truth, with the small deliberate overcorrection of a woman telling the truth for the first time in a long while.

"Occupational," said Dilly.

"Good. I did it to Odessa for thirty years. It was the only way to find out what she wanted." Hester almost smiled. "I am not the one you're looking for. But I know who is in the building, and I think I know who is not supposed to be. I would like to give you something, and I would like you to be very quiet about where you got it."

She went to the wall of binders, took down the thirty-first from the left, and opened it on the desk to a page of dense small print. A column of numbers, times, and plates.

"The garage," she said. "Fairhold owns the lot on the north side of Merchant Street. It has a barrier, and the barrier logs every plate that enters. The security company is bound to report to me weekly. Nobody reads the reports. I read them. I am the only person who reads the reports." She turned the binder around. "Wednesday morning. A vehicle enters at 2:58. Leaves at 3:31. The plate is registered to the Thornquist Family Foundation. The pass number belongs to Greta Thornquist."

The room went very quiet.

"Greta," said Sel.

"Your cousin has a pass to the garage because she chairs the finance committee. She does not have a pass to the vault. But there was an entry at the vault door at 3:12." Hester's pale eyes moved to Dilly. "Margit told me. She came to me on Friday, as one Fairhold woman to another, and said that the founder's card had been used eleven hours after the founder's death. I have not slept since. What I understand, and cannot understand, is how Greta Thornquist, who is a very good accountant and a very poor burglar, came to be holding Odessa's card."

Dilly said slowly, "It was in her handbag. In the bedroom. Bettina sealed the handbag on Tuesday evening with the rest of the effects."

"Yes. And who was in the house on Tuesday evening, offering condolences?"

Nobody needed to say it. Maurice, in a black tie and a gentle voice. Greta at his shoulder, carrying a basket of fruit. And before them, an hour earlier, the doctor who had pronounced her, the cousins and the cooks, Ferdie in his rumpled shirt, thirty people drifting through an open house in the stunned hours after a death, any one of them able to open a drawer.

"Ah," said Sel, to himself. It was a very small sound. "And that is how it is done. One does not break into a house. One attends the wake."

"Greta did not come alone," said Hester. "She had a driver. His name is on the log too. Hal Duggan-Ito. He has been Maurice's driver for eleven years." She closed the binder. "I am telling you this because I am fond of you, Anselm, and because it will hurt, and because I would rather you hurt among friends. You are in a building with a wolf. I do not know which of the sheep she is wearing. I know it is not me. And I know that if you cross this road and are caught, the first thing Maurice will do is take every document in this room to the board and say Hester has lost control of her own tablet. So I'd like very much to give you the log now, and ask that you do not tell me what you do with it."

Sel stood, rather slowly. He put the plate of cake on the desk. He bent, and kissed the top of her head, a tiny precise movement, like a man placing a stamp on an envelope.

"Thank you," he said. "For the bicycle."

"You were very bad at it," said Hester. "Go away. Eat something."

They were in the lift, going down, with the binder page folded into Dilly's jacket. Sel stood against the brass rail with his eyes shut. He had been very still since the sixth floor.

"Greta used to bring me crisps," he said, without opening them. "When I was nine. From the shop on Pellow Road, the salt and vinegar ones. She would put them in my coat pocket at family dinners when no one was looking, and I would eat them in the lavatory. I thought it was the nicest thing anyone had ever done for me."

"People can do nice things and awful things in the same week."

"Yes. I am told that is called a personality." He opened his eyes. "I should like to be angry. I find I have only a very large tiredness. Is that normal, in your profession?"

"In my profession the anger comes later," said Dilly. "First there's a list."

"Of?"

"Who was where. Who had what. Who benefits." She watched the floor numbers fall. "It's a way of not feeling things until you've got the exits covered."

"That sounds extremely efficient."

"It's the only thing I've ever been good at."

"I do not believe that for a moment," said Sel, mildly, and turned his face to the door, and said nothing else, and she found that she did not know where to put her hands. Then her phone buzzed. She took it out. It was her mother, which was strange, because Gulnora Karimova texted twice a year, at Eid and when a customer died.

The message was in Uzbek, in lower case, with no punctuation.

a man came to the shop he said it was for you he put it on the counter and left

A photograph followed. Dilly opened it with her thumb.

It was a pie. A small, perfect, pale pie in a white cardboard box, on the laminate counter between the change machine and the jar of lost buttons. The meringue was whipped into high glossy peaks, golden at the tips. Beside it, propped against the till, was a card in a cream envelope, and on the front of the card, in slanting black ink, was one word.

Hold.

The lift chimed. Sel looked at her face, then at the phone, then at her face again.

"Dilly," he said gently. "Is that lemon?"