The pie sat on the counter like a small white bomb, and nobody in the shop would stop eating around it.

Dilly stood at the door in her funeral shoes with her heart pounding from the stairs and counted what she saw. Her mother behind the till, folding a duvet cover with the unbothered speed of a croupier. Mrs. Okonkwo-Reyes from the flats, in a hairnet, sorting socks. Two students asleep on the bench with their heads against the wall. A man in overalls she half-knew from the phone-repair counter, leaning on the dryer with a cup of tea. A woman from the gym that had been a church, in neon leggings, reading a paperback. And Rustam, on a stool by the change machine, holding his phone in both hands without looking at it, the most disciplined she had seen him in her life.

"You didn't touch it," Dilly said.

"Of course I did not touch it," said her mother. "It is not mine."

"A man left it. Tell me about the man."

"Forty. Maybe forty-five. Courier jacket, yellow, with a bird." Gulnora pressed down a seam. "He says, Karimova? I say yes. He says, for the daughter. He puts it here and he goes. He did not wait for money. He did not smile. I thought, this man has been paid already."

"The bird is Parcelly," Rustam offered. "It's the delivery app. There are about nine hundred of them in town."

"Did he give a name? Show an ID?"

"He wore his glove." Gulnora said it with the weight of an indictment. "A man who wears a glove in a laundry is a man with something to hide."

The man in overalls cleared his throat. "Sorry, Mrs. K. It's seven degrees outside."

"Then he can take it off inside."

Dilly put on gloves of her own, nitrile, from the first-aid kit by the sink, and lifted the lid of the box with the tip of a pen. Meringue. Lemon curd, bright and glossy. Nothing underneath. She turned the box over and looked at the base: a white sticker, the kind a bakery uses for a price, with the number 14.50 in violet ink and the stylised outline of a rolling pin. Under the pie, pressed flat into the cardboard, a receipt slip, curled at the edges, stamped with a time.

10:52 A.M. Today.

Someone had walked into a bakery at ten fifty-two, an hour after she had sat in the Fairhold board room and watched Cyrus Valdivia-Moon's right eyebrow lift a sixteenth of an inch. Someone had bought a pie, written a word on a card, and sent a courier. It was a clean, quick, theatrical piece of work. It was also, she realised, the first time since the day of the clip that anyone had threatened her in language she understood.

"Why are you smiling?" said Rustam.

"I'm not."

"You've got the thing. The corner thing."

"It's nothing." She was, though. She could feel it, faint and unpleasant, tugging the corner of her mouth. "It's just that for fourteen months I've been trying to work out what I did wrong. And somebody just sent me a pie to say I didn't."

The woman in neon leggings lowered her paperback. "Is that her? From the thing? Is it true you're marrying the bank?"

"I'm marrying a man," said Dilly. "He has a bank."

"It's the same thing," said Mrs. Okonkwo-Reyes, from the socks, and the whole shop agreed.

It was only then, as she straightened, that she noticed the other thing. A whiteboard on the wall by the door, where her mother usually wrote the price of dry-cleaning and the days the boiler might fail. Someone had cleaned it. In its place, in blue marker, in a handwriting she did not know, was a grid with seven columns and five rows, filled with names. Mondays: Femi, Dot. Tuesdays: Imran, Lakshmi. At the top, in capitals and underlined twice: DRAY STREET WATCH. SOMEBODY IS ALWAYS HERE.

"What is that?"

Gulnora, still folding, did not look up. "Mr. Paresh from the phone shop made it on Thursday night. After your face was on the internet. He says nobody comes to my laundry and sends me a bad surprise."

"Ona, those are your customers."

"Those are my neighbours." It was the first time Dilly had ever heard her mother use the word as if it had a smell. "You think I have spent twenty years washing the shirts of this street and I do not know what to do when someone leaves a pie? I did not ask. They came. They sit. They fold. I have never had so many people fold."

The man in overalls lifted his tea. "We've done shifts since Friday," he said. "Nothing happened until today. It's a very quiet street. Is there any chance we could have a nice bit of that pie?"

"No," said Dilly and Gulnora in unison.

Sel came at two. He came on foot, with Pascual three paces behind, and Junie behind Pascual with a laptop open on her forearms like a waiter's tray. He stopped in the doorway, looked at the whiteboard, at the rota, at the dozen people in the shop pretending not to look at him, and said, very gently, "Good afternoon. I am the person you're protecting her from."

A ripple of laughter went round the room.

"He is better in a cardigan," Mrs. Okonkwo-Reyes told her neighbour, not quietly.

Dilly steered him into the back room, among the stacked soap and the boiler, and closed the door. She showed him the card. She showed him the receipt, the sticker, the courier jacket. She laid it all out on the ironing board like evidence on a table. Sel studied it with his hands behind his back.

"A bakery on Pellow Road," he said. "Violet ink. That will be Loafer's. Everyone in the district buys there. It is also the bakery whose owner has a Fairhold mortgage."

"So you can find out who paid."

"I can't."

She stared at him.

"The bakery uses Tally. The customer will have paid at the till with a phone, a card, or cash. If Tally, there is a transaction record. And I could, with a word, read it." His voice had flattened, the way it did when he was reciting something learned by heart. "My grandmother wrote it into the charter in nineteen sixty-five. It is called the Founder's Rule. No officer, executive or member of the Foundation shall examine, trace or disclose an individual's account without that individual's written consent or a court's warrant. A bank that looks is a bank that sells. She said it so often that I thought it was a nursery rhyme."

"Sel. Someone is threatening my mother."

"I know."

"A man in a glove put a pie on her counter. The next one may not be a pie."

"I know that, Dilly." He turned from the ironing board and met her eyes. "And if I break the Rule today for you, then on Thursday Maurice breaks it for the board, and on Friday some junior clerk looks up the account of the woman he wants to date, and the week after, the city discovers that Fairhold reads its secrets. It is the only promise we have ever made that people believe. I cannot spend it on a pie."

Her first instinct was to be furious. It rose up through her as fast as flame through paper. It was the same fury she had felt at the blue pad when she was nineteen, in a line of strangers, reading a word that was true and unkind. She said, with great care, "My mother is the pie."

"Yes."

"I'm asking you to look."

He stood very still. She watched the argument in him, the long, painful, honourable one, move behind his face. When he spoke again he sounded older.

"There is an exception," he said. "It is the only one. The Founder's Glass. The Keeper may, once a year, in the presence of the Vault Clerk, with both signatures in the ledger, open a single account. One. For a reason he is prepared to write down, to be read aloud at the next Close. Odessa used it twice in sixty years. The first time was for a man who was stealing from widows. The second I never learned." He paused. "I have not used it. I thought it would be for something larger than this."

"It's my mother," said Dilly.

Sel nodded. "Then it is not smaller."

Margit was sent for. She arrived in forty minutes in her good grey coat, took in the pie, the sticker, the ironing board and the tension between the two of them, and said, "I shall need a pen. And a witness who is not either of you. Junie, would you stand there, please, and not narrate."

"I never narrate," said Junie, narrating.

It happened on Junie's laptop on the ironing board, in the damp-smelling back room, among the soap flakes: a grey screen with a dated header, a space for a reason, a signature line for each of them. Sel typed, slowly, two sentences. Margit read them aloud in her dry flat voice. They signed. A small blue hand blinked on the screen, and a window opened with a single transaction.

Bakery, Loafer's of Pellow Road. 10:49 A.M. $14.50. One lemon meringue pie, to go.

The account that had paid for it was listed below, with its name and a small grey icon that Dilly had seen only on billboards. A neat, clean, corporate account with a gleaming tag.

ARDENT NATIONAL BANK. CORPORATE HOSPITALITY. CORLISS FERRY.

Nobody spoke for a moment. Junie, for once, made no sound at all.

"He paid with his own company's card," said Dilly, slowly. "To a bakery. On the street where the bank he wants to buy is. He used the name."

"He did not need to," said Margit. "He could have used cash."

"No." Sel was looking at the screen, and his face had gone very still and remote, as it did when he was at the desk on the stroke of eleven fifty-eight. "He wanted us to see it. This is not a secret, Dilly. It is a signature." He took a breath. "Mr. Valdivia-Moon has just told us he is not afraid of us, and that he knows precisely how much we will not be able to prove."