The body had already been removed by the time Sloane Mercer reached the twelfth floor.

She knew before the elevator doors opened. The hallway had the wrong silence — not the silence of an empty corridor, but the silence of one that had been recently full and was now being kept that way. There were two men in dark coats standing at the entrance to the apartment, and neither of them looked at her face as she approached. They simply stepped aside.

That was the first wrong thing.

The second was the smell. Mayfair apartments at this price point smelled of nothing — that was what you paid for. This one smelled of cleaning solvent. Recent. The kind a building's service team used in the half hour between a problem ending and the building deciding the problem had never existed.

Sloane stopped just inside the doorway. She did not remove her gloves yet.

The apartment was beautiful in the way Mayfair apartments were always beautiful — high coffered ceilings, wide oak floors bleached to a bone-pale gray, floor-to-ceiling windows holding a careful slice of the Thames. Nothing on the surfaces. Nothing out of alignment. The kitchen, just visible through the open archway, looked the way a kitchen looks when no one has ever actually used it.

A man cleared his throat behind her. Mid-forties. Building staff, by his coat. A voice that had practiced sounding helpful.

"Ms. Mercer?"

"Give me a minute."

She did not turn. She stood in the threshold and let the room finish settling. There was a near-invisible compression in the rug fibers next to the sofa — the weight had been there long enough to leave a mark. There was a single side table whose alignment was a degree off from the line of the sofa, which meant someone had brushed against it recently and corrected it imperfectly. The marble counter in the kitchen had been wiped, but not in the pattern of a regular cleaning; it had been wiped the way you wipe a counter when you want one specific area cleaner than the rest.

A man had died in this room within the last six hours. He had died near the sofa. He had died without struggling. And then a very disciplined set of people had spent ninety minutes turning the room back into a brochure.

"Cause of death," Sloane said, still not turning.

"Preliminary is overdose, Ms. Mercer."

"And what was found on him."

A beat of hesitation. Then: "Nothing."

She let that sentence sit in the air for a moment. Most people, even professionals, would have filled the silence after it. The man behind her did not, which was an unhelpful kind of competence.

"A man," she said quietly, "who lives in an apartment this disciplined does not lose control thoroughly enough to die, then maintain enough composure to dispose of the evidence before his heart stops."

She heard him shift his weight. He still did not respond.

Sloane finally removed her gloves and slid them into her coat pocket. She crossed to the windows. London moved below her in the late-afternoon gray, a city engineered around the assumption that nothing of consequence ever happened in apartments like this one. From this angle, the river looked older than the buildings on either side of it. That was the thing she liked about the river. It did not pretend to be on anyone's side.

Her phone vibrated once against her hip. She did not reach for it.

Outside, a thin rain had begun to fall against the glass — the slow, indecisive London rain that never fully committed and never fully stopped. Below, on the pavement, a black sedan idled at the curb. She watched it for a long moment without turning her head.

Then she watched it pull away.

It had not been waiting for a passenger. It had been waiting to see her enter the building.

She let her hand settle against the cold glass. She had been in this work for almost twenty years. She had seen disciplined deaths before. She had seen rooms cleaned. She had seen, on three occasions in her career, men of significant influence quietly disappear inside their own apartments without leaving the kind of trace that a defense attorney could later use.

This was the cleanest one she had ever stood inside.

She turned, finally, and looked at the man in the doorway. He was waiting with the patient blankness of someone who had been told not to comment on what she did next.

"Who called this in?" she asked.

"His firm. A morning wellness check."

"Door was locked."

"Double-locked from the inside. Smart system shows no entries after eight last night."

She nodded once, slowly, and reached into the inside pocket of her coat for the small lead pencil she had been carrying since her grandfather had taught her, forty years ago, to make notes in something that could be erased. She flipped open the legal pad in her left hand.

At the top of a fresh page, she wrote four words in clean, ungenerous block letters.

This death was introduced.

She underlined the word introduced.

Then she closed the pad and walked back into the room, and began.