The fog rolled through Mayfair like a living thing, thick and yellow and smelling of coal smoke and something older. Evelyn Ashworth stood at the window of her father's study and watched it consume the gas lamps one by one. It had been three weeks since the funeral. Three weeks since she had returned to this house on Grosvenor Square and discovered that grief was not the heaviest thing in this house.

The resonance器 sat on her father's desk, wrapped in oilcloth. She had found it beneath a stack of engineering journals, its brass fittings tarnished to the colour of old teeth. It was not large—no bigger than a writing box—but it was heavy, heavier than brass and crystal and copper wire had any right to be. When she had first unwrapped it, the air around it had hummed, a vibration so low she felt it in her teeth rather than heard it.

She should have told Lord Blackwood. She should have called for a physician, or an engineer, or anyone. But Evelyn was twenty-four, unmarried, and possessed of her father's stubborn curiosity, and she lifted the crystal lens and looked through it.

The room did not change. The oilcloth, the desk, the gas lamp on the desk—all remained as they were. But behind them, superimposed like a photograph developed beneath a photograph, she saw another room. Herself, younger, perhaps twelve years old, standing beside her father's bed. Her mother—dead ten years—leaning over her, her face pale but smiling. Her father's hand on her hair. The date, scratched into the bedpost by some childish knife: 14 March 1862.

Evelyn gasped and stumbled back. The crystal fell from her hands and rolled across the desk, coming to rest against a brass gear. The image faded. The room was only a room again.

She sat on the floor for a long time, breathing carefully, as though loud breathing might disturb something fragile. Then she picked up the crystal and looked again.

---

The first death was Mr. Harrington, the family solicitor.

Evelyn had seen him in the resonance器 three times before she understood what she was seeing. In the first vision, he was in her father's study, late at night, speaking in low tones with Lord Blackwood. Blackwood held a document—Evelyn could see the seal, the Royal Society's seal—and Harrington was shaking his head, saying words she could not hear. In the second vision, Harrington was alone in the same room, copying something onto a smaller document. In the third, he was leaving the house, his face pale, his hat tilted at an angle Evelyn had never seen him wear.

On the fifth day after she first saw him, Mr. Harrington fell from the stairs of his office in Lincoln's Inn. The coroner's verdict was accidental death. Blackwood attended the funeral and placed a hand on Evelyn's shoulder, his fingers heavy and warm.

"You must be strong, Evelyn," he said. "Your father's work continues. Ours must continue with it."

She nodded because that was what one did. But that night, she took the resonance器 to her bedroom and looked through the crystal until the gas lamp burned low.

She saw Harrington again. This time he was not speaking with Blackwood. He was speaking with a woman—Evelyn could not see her face, only the back of her head, dark hair pinned severely. She was sitting in her father's armchair, the one that now sat empty in the study. Harrington was saying something urgent, something that made the woman stand up. She walked to the window and looked out—at Evelyn's room, perhaps, or at the garden where Evelyn had played as a child. Then she turned and said something to Harrington, and he nodded, folded the document, and placed it in his coat.

Evelyn did not sleep. She sat in her chair by the window and watched the fog move through the garden, swallowing the rose bushes, swallowing the path, swallowing the world.

---

The second death was Thomas, Sarah's lover.

Sarah was the maid who cleaned Evelyn's rooms. She was twenty, from Bethnal Green, with bright eyes and a habit of humming when she thought no one was listening. Thomas worked at the docks. He was tall and quiet and looked at Sarah the way a man looks at something he knows he cannot keep.

Evelyn saw them together in the resonance器 on a Tuesday morning. They were in a tavern near the Thames—Evelyn recognized the wallpaper, the cracked mirrors, the bottle of port on the table. Thomas was speaking urgently, his hand on Sarah's wrist. She was shaking her head. He pressed something into her palm—a coin, or a token, Evelyn could not tell—and then he was gone, swept out of the vision as the crystal shifted to show Blackwood entering the house with a man Evelyn did not recognize.

On Thursday, Sarah did not come to Evelyn's rooms. On Friday, the housekeeper said Sarah had left, suddenly, in the night. On Saturday, Evelyn learned that Thomas had disappeared as well. A labourer from Bethnal Green reported him missing to the constable. No one had seen him since Wednesday evening.

Evelyn went to the resonance器 and looked until her eyes burned.

She saw Thomas at the docks, speaking with men in dark coats. She saw him hand them a document—the same shape as the one Harrington had carried. She saw him walk away alone, his shoulders hunched, and then she saw men in dark coats follow him into an alley. She did not watch what happened after that. She could not.

She wrapped the resonance器 in oilcloth and carried it to the cellar, where the coal was stored. She stood over it with a shovel raised, ready to strike the crystal to pieces, and then she lowered the shovel. What if there were more? What if there were truths she needed to see?

She carried it back upstairs.

---

The third death was the one that came for Evelyn herself.

She told herself she would look only once more. Only to find out what the woman in the vision had been saying to Harrington. Only to know.

The crystal showed her her father's study, but not as it was— as it had been, six months ago, before the illness. Her father sat in his armchair, weaker than Evelyn had ever seen him, his face grey. Blackwood stood beside him, his hand on her father's shoulder. The woman—the same woman from the tavern—sat in the chair across from them. Evelyn could see her face now. She was perhaps fifty, severe, beautiful in the way a knife is beautiful.

"She knows too much," the woman was saying. Her voice, filtered through crystal and time, was flat and precise. "The children will inherit more than property. They will inherit knowledge."

Her father was shaking his head. "Evelyn is a child."

"She is your daughter," Blackwood said. "That makes her more than a child and less than a protector."

The woman reached into her bag and produced a small vial. She placed it on the table between them. Evelyn leaned closer, her breath fogging the crystal.

"What is that?" she whispered, though no one could hear her.

"Laudanum," her father said, and his voice was different now—smaller, afraid. "Too much, and it stops the heart. Too little, and it brings sleep."

"You are ill, Arthur," the woman said. "The doctors agree. It would be a mercy."

"I am not—"

"You are." Blackwood's voice was gentle, almost kind. "And when you are gone, the research will be secure. The children will be provided for. Everything will be as it should be."

Evelyn pulled away from the crystal. Her hands were shaking. She pressed them against her mouth to stop the sound that was building in her throat.

Her father had not died of illness. He had been poisoned. By his brother. By a woman he had trusted. By the man who now stood beside his bed at the funeral and placed his heavy hand on Evelyn's shoulder.

She wrapped the resonance器 in oilcloth one final time. She did not take it to the cellar. She took it to the garden, to the family graveyard behind the church where her parents and her mother and her younger brother were buried. The fog was thick, thicker than Evelyn had ever seen it, and the gas lamps had been extinguished. She knelt on the damp earth between the headstones and unwrapped the crystal.

She looked at the graveyard as it had been, fifty years ago. She saw graves being dug, bodies being lowered, men in dark coats standing in a circle around a grave that was too small for the man inside it. She saw Old Man Baptiste—she recognized his name from the parish records—being forced to his knees, his hands bound, his mouth open in a scream that no one in the fog could have heard.

The crystal showed her everything. It showed her the wealth of the Ashworth family, built on a crime buried in damp earth. It showed her Blackwood's hands, younger, tying the ropes. It showed her her own face, reflected in the crystal, pale and terrible and knowing.

She set the crystal down on the earth between her father's grave and her brother's. The fog moved around her like a curtain. She could hear the church clock striking midnight, twelve times, each note swallowed by the fog before it could travel far.

When Lord Blackwood found her in the morning, she was sitting exactly where he had left her, her hands folded in her lap, her eyes open and fixed on the headstone of a man who had been dead for fifty years.

She was not breathing.

The coroner's verdict was heart failure. Blackwood attended the funeral and placed a hand on the housekeeper's shoulder.

"You must be strong," he said. "The work continues."

In the graveyard, between two unmarked stones, the crystal lay in the damp earth, waiting for someone to pick it up and look through it.