Marco's envelope was waiting beside her plate on Friday morning, and it was thicker than she had expected.

Sienna turned it over in the long white kitchen with the sun coming through the tall windows and Mrs. Venn pretending not to watch from the range. The flap was sealed with a plain wafer of red wax, unmarked. Inside lay six typed pages, stapled at the corner, and a smaller sheet of ruled paper folded in half. She tested the paper out of habit, felt foolish, and read.

The list was in alphabetical order and thorough to the point of obsession. Thirty-four names. The cook and his two kitchen boys. Four waiters hired from an agency on Calloway Street, with the agency's registration number. The florist, the man who had delivered the ice, the quartet who had played in the ballroom, a boy of fifteen who had carried chairs. Beside each name ran a column in Marco's small square hand: where the person had stood, what they had touched, and for how long. Someone had gone through the whole bright chaotic day with a stopwatch.

The ruled sheet was shorter. It had been written in the same hand, in pencil, and it carried no greeting.

The flutes left the house on 30 September, by courier, at the written instruction of Mr. D. Vance. They were taken to the clinic annex for sterilization at the written request of Dr. H. Roux. They returned to the library on the morning of 8 October, sealed in the blue leather box. No one else handled them. I have asked twice.

She read it a second time, slowly, and the kitchen seemed to tilt a few degrees.

Mrs. Venn put a cup of coffee in front of her, with a saucer and a pinch of gray salt on it, and said nothing at all.

"Thank you," Sienna said absently.

"He was up at four again," Mrs. Venn said to the range. "Sat at that table for an hour with the list. He'd have given his right hand to hand it to you himself, only Marco said you'd sooner read it alone." A pause. "Marco's usually right about that sort of thing. It's very irritating."

Sienna looked up. There was nothing on the stout, weathered face but a polite blankness, but one eyebrow had lifted a quarter of an inch, and she felt her cheeks warm. She dropped the salt into her coffee, stirred it, and did not trust herself to answer.

The clinic annex stood at the north end of the house, where the lawn met the pines, and she had never been inside it. In the other life she had never been anywhere in this house except a ballroom, a cloakroom, and a bridal suite. The thought followed her down the gravel path in the thin morning sun, along a hedge of box and a border of tired late roses. A small glass-roofed building, a converted conservatory, stood at the end of the path, its panes whitewashed to the height of a man's head. A brass plate beside the door read: DR. H. ROUX. BY APPOINTMENT.

She had made one. It had taken a single telephone call to the library, and Mrs. Venn had arranged it with such alacrity that Sienna suspected the household had been hoping for it. The pretext was easy and almost true. A new member of the family ought to be examined. She would like her own baseline numbers on file, in case anything should ever need comparing.

She tested the door handle with the back of her glove before she touched it, and then, annoyed at herself, took the glove off and went in with a bare hand.

Inside, the room was cool and bright and smelled of antiseptic and cut lemons. White tile, steel cabinets, a high padded couch under a window. A glass-fronted cupboard of instruments. A desk covered with files in neat colored folders, and a vase of white freesias on the sill. Through an open door at the back she could see a second, smaller room, and the steel curve of a large machine on a counter: an autoclave, squat and gleaming, with a heavy round door and a row of dials.

"You're early," said Helena Roux.

She was standing at the desk with a pen in her hand, a tall woman in a white coat over a dark dress, her sleek black hair tucked behind one ear. The gray eyes were exactly as cool as Sienna remembered. But when she turned there was a fractional pause, the barest hitch, as if she had expected to see someone else.

"I was told ten," Sienna said.

"It's ten." Helena glanced at the wall clock, which said nine fifty-two, and smiled very slightly. "I suppose I'm slow. Sit down, please. Will you take tea?"

"If it's no trouble."

It was a trap, of a kind, and Sienna was not sure which of them had set it. Helena made the tea herself, at a small tray in the corner, with her back turned. When she brought the cup, she set it on the desk before Sienna and did not offer the milk. Sienna drew a strip from her pocket without a word, dipped it, and watched it stay yellow.

"You needn't do that here," Helena said evenly.

"I know."

"I mean it as a courtesy. I'd think less of you if you didn't." The gray eyes rested on the strip. "Dr. Pryce taught you well. He taught me too, a lifetime ago. He used to say that a good analyst trusts no sample she hasn't run herself."

"He says it still."

"I'm sure." Helena lowered herself into the chair behind the desk, and her face did something small and unreadable. "Well. Let's begin."

The examination was thorough, impersonal, and almost insultingly competent. Helena took blood from the crook of Sienna's arm with a single clean stick, checked her pulse and pupils and reflexes, listened to her chest, and asked a long series of questions about family history in a voice that never changed. It was the voice Sienna heard every day from the senior doctors on the third floor. It asked nothing it did not need to know. It gave nothing away.

While the tube filled, Sienna looked past Helena's shoulder at the open door of the little back room, the steel machine, and a small spiral-bound book chained to a hook beside it.

"That's a handsome piece of equipment," she said.

Helena did not look around. "The autoclave? It's thirty years old. It ought to have been replaced in the nineties, but this family would rather put a second mortgage on a ship than buy a new sterilizer." She pressed a cotton ball to the puncture and bent Sienna's arm. "Hold that, please."

"It works properly?"

"Impeccably. I'd stake my license on it."

"That's good to know." Sienna kept her tone idle, and felt her heartbeat tick up a notch. "I understand you sterilized the wedding crystal in it. Dario's gift. He said you had them cleaned."

The silence lasted a quarter of a second.

It was so short that a person less practiced would have missed it. Helena's hand, resting on the table, stopped moving. She looked up from the cotton ball with her gray eyes level and her face calm, and in the gap before she spoke, something passed behind the calm, quick and cold and very far down.

"Yes," she said. "Dario asked me to. Old glass can hold all manner of things. He's very careful about that sort of detail."

"When did you do it?"

"I couldn't tell you the day."

"The sixth," said Sienna, "I thought. Or the seventh. Was it you who ran the cycle?"

She had not meant to say it. It had come out of her mouth the way her mother's voice sometimes came out, with a life of its own. She felt the muscles in her arm tighten under the cotton. Helena went very still, and for the first time since Sienna had walked in, her eyes dropped. It was only for a moment. They fell to the open door of the back room, and to the little spiral-bound book that hung from its hook.

"Dr. Roux," said Sienna gently. "I'm only curious. It's a professional vice."

"I was in Carrow that week," Helena said.

"Were you?"

"A conference. The fourth to the eighth. I took the early train on the fourth, and I came back on the evening of the eighth." She spoke slowly, and each word was set down with great precision, like a woman crossing a stream on stones. "I wasn't in the house at all. I had my assistant arrange the sterilization before I left."

"Of course."

"There is a log. Everything is in the log."

"I'm sure it is."

Helena rose. "I'll just fetch the cuff for your pressure," she said, and went through the open door into the small back room, with her white coat snapping at her heels.

Sienna did not hesitate.

She was on her feet and across the tile before she had time to think about it. The spiral book hung from its hook at the end of a short chain, and it fell open in her hand as if it had been opened a hundred times. Columns of dates. Columns of times, the cycles run, the temperatures reached, the initials of whoever had done it. A tidy blue ink. She turned the pages with her thumb, back past the third and the second and the first of October, and stopped.

September 30. 2:10 a.m. Cycle 4. Glassware, 2 pieces, crystal. 134 degrees, 20 minutes. H.R.

October 6. 2:40 a.m. Cycle 2. Glassware, 2 pieces, crystal, second pass. 134 degrees, 20 minutes. H.R.

The handwriting was small, upright, precise. The two sets of initials were identical down to the loop of the R. And Dr. Helena Roux had been, by her own word, on a train to Carrow from the early morning of the fourth to the evening of the eighth.

Sienna looked at the date for a long time.

There were two possibilities, and neither of them was comfortable. Helena had lied about where she had been. Or someone else had signed her initials into the book, in a hand so like hers that no one would think to question it.

Her fingers found the edge of the page. She heard footsteps, quick and light, on the tile in the back room. She let the book drop on its chain and was back in the chair, with her arm bent and the cotton ball held tight to her elbow, before the door opened.

Helena came out with a blood pressure cuff in one hand. She looked at Sienna. She looked, briefly, at the book, hanging a little crooked on its hook. And then she smiled, and it was a perfect, composed, professional smile, and it did not reach her eyes at all.

"Does he know you're here?" Helena said quietly.

"Matteo? I told Mrs. Venn."

"That isn't what I asked."

The cuff hissed around Sienna's arm. A cold, sharp curl of unease went up her back, and she did not know whether it was fear or warning. Helena's face, bent over the dial, had changed. It was still smooth. But the smoothness looked like a surface drawn very tight over something that was shaking.

"I think," said Helena, so low that it was barely a breath, "that you are far cleverer than is safe in this house. I'm telling you that as a physician. I would not say it twice."

"Is that a warning or a threat?"

"It's a blood pressure reading," said Helena. "One-twenty over seventy-eight. You are in excellent health."

The door opened.

It did not slam. It opened with the careful, unhurried sound of a door pushed by a man who knew exactly how much noise it could make. A cool wind came in from the pines, smelling of resin and wet earth. Sienna turned her head, and the air in the room changed.

Matteo stood on the threshold with the light behind him.

He had come straight from the quay. He wore a gray overcoat, unbuttoned, over a dark suit, and the salt wind had pulled his hair into a careless, dark disorder. His hands were in his pockets. He looked relaxed, even idle. Only his eyes, moving once across the room, from Helena's face to the cuff on Sienna's arm to the little book on its hook, were not idle at all. They were sharp and dark and very still, and they took in everything.

"Dr. Roux," he said pleasantly. "Forgive the intrusion. I was told my wife had an appointment."

"A routine examination," said Helena. She had straightened up, and the white coat hung from her shoulders like a flag at a funeral. "I've only just finished the pressure."

"I'm glad to hear it."

He came in. He crossed the room without hurry, the length of the white tile, and stopped behind Sienna's chair. She did not turn her head. She felt him there, tall and warm, a breath's width from her shoulder, and every nerve in her back stood to attention. He did not touch her. He did not lean down. He only stood, with his hands in his pockets, and let the quiet gather, and the very air between them seemed to thicken and grow warm.

There was something deliberate in it. She could hear the intention in the stillness, and she understood what it was. It was not possession. It was a wall. A man was standing between her and the rest of the room, and he was doing it with nothing but his own body, and he had not once raised his voice.

Her pulse, absurdly, would not slow. Under the cuff on her arm, it beat against the rubber, a quick traitor's drum, and she knew that Helena could see it on the dial.

"Is everything in order?" said Matteo.

"Entirely," said Sienna, and was proud that her voice held.

Helena stripped the cuff from her arm. She wrote a number on a card and slid it across the desk. Her hands were steady. "The blood results will be ready on Monday. I'll send them to the library." She hesitated. "If you wish, Miss Hale, I'd be happy to answer any other questions about the clinic. I have nothing to hide."

"I'm sure you don't," said Sienna.

She rose. She felt him step back, to give her room, with the same exquisite courtesy, and she turned and saw his face for the first time in the clear white light. It was composed, and gentle, and beneath it a muscle jumped at the hinge of his jaw. He was angry. She had never seen him angry, not really, not like this, a cold, banked, patient fury that rolled off him like frost off a window. And it was not directed at her.

Helena inclined her head. "Mr. Bellandi."

"Helena." A pause. "Thank you for looking after her."

It was the lightest of sentences. It was only courtesy. But something moved at the back of Helena's gray eyes, and she looked away.

They went out into the thin bright wind, and the glass door swung shut behind them with a soft metal click. The pines hissed. A crow lifted off the lawn and settled again. For a few steps neither of them spoke. He walked at her left, with his hands in his pockets and his head bent, and she kept her own eyes on the gravel path and the long line of tired roses along the hedge.

"She lied about the sixth," Sienna said.

He did not break stride. "Yes."

"You know."

"Marco went through the clinic's records last night." A faint, dry breath. "I'd rather he hadn't had to. He told me about the book. I did not know whether it was safe to say so to you in front of her, so I thought it better to come myself." He glanced down at her. "I hope I did not intrude."

"You did," said Sienna. "A little."

"I'm sorry."

"No." She stopped. They were at the end of the hedge, beside a stone bench, with the pines rising dark behind it and the pale line of the sea beyond. "I'm not sorry that you came. I was glad. I wanted you to know that."

He stood very still, and a slow color crept up from the collar of his coat. It was a strange thing to watch a man like that blush. He looked at her, and then at the sea, and then at her again, as though she had said something in a language he had once known and half forgotten.

"Helena is a suspect," said Sienna, to cover it. "She had access. She had the means. She lied about the dates, and then she tried to frighten me, or warn me, I'm not sure which. It all fits."

"Yes."

"Too neatly."

He turned his head. "Go on."

"A person who really meant to kill someone in that room wouldn't initial the book. She wouldn't sign it with her own name on a day she had told me she was out of town. Either she's a fool, or she's very clever, or someone wants me to think she's one of those. The list is thirty-four names. Helena's the only one I can see so far, but I don't believe she's the only one who could have done it." She drew a breath. "I'd like to know who else had access to her handwriting."

He said nothing for a moment. His eyes had gone to the horizon. A gull wheeled out over the water and cried once, thin and harsh.

"Helena is not the only name on that list who matters," he said. "I'm sure you've seen it."

"I've seen it."

"Whoever did this did not need long in the room. A minute. Less. Someone who knew when the maid would leave and when you'd be dressing, and who could set it all out and walk away before anyone thought to look." His voice dropped. "Whoever left the card didn't need to be there for more than a minute."

The wind stopped.

Sienna did not move. She did not breathe. She stood with her hand on the cold stone of the bench and her eyes fixed on the sea, and a tide of ice rose up from her feet through her knees and her hips and her ribs, until it reached her heart and closed around it.

She had not told him about a card.

She had not told anyone. There had been no card on any sideboard in this life. The room was bare. The sideboard had been taken away, the wallpaper repapered, the lamp changed. There was no ribbon, no ice bucket, no white bottle, and no note. Only she had stood in a bridal suite a year from now and watched a small cream-colored card slide out from under a ribbon. Only she had seen the way a man's face went blank when he read it, and the way he folded it into his pocket, and said nothing.

There was a silence behind her, thick and sudden.

She did not turn around. She did not need to. She heard him draw a breath, a long, careful breath, as a man does who has stepped onto ice and heard it speak. She heard it catch. She heard him say, very quietly, "Sienna."

The crow lifted off the lawn behind them and flew away over the pines.