She was sopping wet, deep in thought. She had stood beside a lion. Perhaps she had more courage than she’d imagined. She dressed and made the walk back home. When she reached the house, she sneaked inside, then left her sandy boots in the hallway and hung her cloak on a brass hook. Water had taught her how to move lightly, and she floated down the hall. The Professor had come up from his workshop and was asleep in the library, exhausted from the trials of his work, sprawled out in a chair. Coralie studied him from the doorway. How deeply he slept, how completely at ease he seemed, as if the world belonged to him and him alone. She drew closer to his sleeping form and leaned down, making no noise as she took the keys from his pocket. She had often sat beside the tortoise and had matched her breathing to echo that of the sea creature’s. She practiced this technique now, slowing her breath and heart and blood.

In the kitchen, the white enameled stove gleamed. A supper Maureen had left for them earlier remained untouched in the cooking pot. Coralie took the cellar stairs in her bare feet. The floor was nothing more than raked dirt, and there were often mice in the corners. An earthy odor of roots mixed with the tang of chemicals. Coralie fitted the two keys into their locks simultaneously and turned them. There were two soft clicks. She let her eyes adjust to the dark before crossing the threshold. Once she was inside the workshop, the scent of formaldehyde was stronger, nearly overpowering. There were rows of teeth in jars set on a shelf alongside dozens of yellowing books. Nearby was the rack of tools, hammers and awls and saws in varying sizes, from one so tiny it could fit in the palm of a child’s hand to an enormous wood saw. Because it was a humid night the cellar was especially damp, the air sweetened with turpentine and wild gum. There was a dark concoction on the desk as well, a sticky tar-like stuff kept in bottles that Professor Sardie rolled into beads to smoke in a pipe that let off a pungent stink.

A wooden crate more than five feet long took up most of the tabletop. As Coralie approached she found herself counting, as if that task would keep her fear at bay. She pushed on the cover so that it slipped forward. Inside, the crate was packed with solid carbon dioxide that appeared as snow. Curls of moisture rose up, which she waved away so she might peer inside. Coralie spied a shimmer of pale hair, the glimmer of flesh. The girl from the river, her blood replaced by formaldehyde, her world reduced to ice. This was her resting place, a box that would have been better used on the docks to pack bluefish or mackerel for delivery to the markets.

Coralie shoved the cover back in place and stood facing away from the coffin, shivering, as if she were the one dressed in chemicals, bloodless and pale. Without another thought, she went to search for the handbook, driven to discover what her father’s plan might be. The room was dark and the items in the drawer were mere shadows to her eyes, but she grasped around until she found what she wanted, her hands fitting over the cover of smooth Moroccan leather. She had wanted to read her father’s diary in its entirety, but there was no time for that. She swiftly thumbed through, finding the last page he’d written upon. The date was this very day, the ink fresh, an indigo blue he favored, the color of water.

Many of the Professor’s notes were in French, and Coralie understood several phrases. Je vais créer ce que je n’ai pas. De chair et le sang. De coeur de l’imagination. But even without written explanations, the ink-stained sketches made his intentions quite clear. He planned to give the city of New York a variation of the trick for which he had been famous, half a woman. This creature, however, would be as monstrous as she was beautiful, a woman joined with a fish, stitched scale to flesh to become a real mermaid, the Hudson Mystery, a far better invention than Barnum’s Feejee Mermaid.

Coralie thought of Maureen’s warning: if you saw the dead twice you were doomed to be haunted. Indeed, the two young women seemed joined by strands of invisible thread, a single being, though one breathed and one was forever still. As Coralie turned to leave, she observed a jumble of belongings on the countertop. A comb, hairpins, a gold locket. She couldn’t bear to see how carelessly these mementos had been tossed into a pile beside surgical tools and bits of bone. She scooped them up, hoping the tokens were so small and unimportant in her father’s eyes he wouldn’t notice their absence.

She left, tugging the door closed behind her, then quickly turning the locks. The cold had seeped into her blood and her eyes stung with tears. She knew that a monster should not feel anything, not sorrow or regret. She should not weep, or shiver, or sob. To do so would only cause her to give herself away and make herself a target. Better to slink through the dark as she did now. Through the kitchen, down the porch steps, into the yard. In the dark the newly greening leaves appeared black. Out at sea there was a foghorn, for the fog that often arose on spring nights had begun to roll in from the shore, blanketing the neighborhood. It was nearly impossible to see two feet in any direction. Still, Coralie could smell an acrid scent and she spied a flash of red sparks. In the corner of the yard wisps of smoke rose from the trash pile, though it was not trash-burning day. Earlier in the evening, while Coralie was at the shore, the Professor had hurriedly disposed of evidence. But he hadn’t done a thorough enough job. Coralie recognized the blue coat. She grabbed for it, though bright embers burned her fingers. She carried the singed coat to the well in the yard and hurried to work the pump, forcing a stream of water out. The fabric sizzled as the flame was extinguished, with a gasp resembling a human sigh.