“Leave us now, Miranda,” said Mrs. Black, who was spinning the heavy brass globe they kept on the desk with one plump, white-gloved finger. Tessa had many times tried to get a better look at the globe—something about the way the continents were laid out had never looked quite right to her, especially the space in the center of Europe—but the sisters always kept her away from it. “And shut the door behind you.”

Expressionless, Miranda did as asked. Tessa tried not to wince as the door shut behind her, closing off what little breeze there was in this airless place.

Mrs. Dark tilted her head to the side. “Come here, Theresa.” Of the two women, she was the more kind—more likely to wheedle and persuade than her sister, who liked to convince with slaps and hissed threats. “And take this.”

She held something out: a dilapidated bit of pink fabric tied in a bow, the sort that might be used as a girl’s hair ribbon.

She was used to being handed things by the Dark Sisters now. Things that had once belonged to people: tie pins and watches, mourning jewelry, and children’s toys. Once the laces of a boot; once a single earring, stained with blood.

“Take this,” said Mrs. Dark again, a hint of impatience in her voice. “And Change.”

Tessa took the bow. It lay in her hand, as light as a moth’s wing, and the Dark Sisters stared impassively at her. She remembered books she had read, novels in which characters were on trial, standing quaking in the dock at the Old Bailey and praying for a verdict of not guilty. She often felt she was on trial herself in this room, without knowing of what crime she stood accused.

She turned the bow over in her hand, remembering the first time the Dark Sisters had handed an object to her—a woman’s glove, with pearl buttons at the wrist. They had shouted at her to Change, had slapped her and shaken her as she’d told them over and over again with rising hysteria that she had no idea what they were talking about, no idea what they were asking her to do.

She hadn’t cried, even though she’d wanted to. Tessa hated to cry, especially in front of people she didn’t trust. And of the only two people in the world she trusted, one was dead and the other imprisoned. They had told her that, the Dark Sisters, had told her that they had Nate, and if she didn’t do what they said, he would die. They’d showed her his ring, the one that had been her father’s—stained with blood now—to prove it. They hadn’t let her hold it or touch it, had snatched it back as she’d reached for it, but she’d recognized it. It was Nate’s.

After that she had done everything they’d asked. Had drunk the potions they’d given her, done the hours of agonizing exercises, forced herself to think the way they wanted her to. They’d told her to imagine herself as clay, being shaped and molded on the potter’s wheel, her form amorphous and changeable. They’d told her to reach down into the objects they’d given her, to imagine them as living things, and to draw out the spirit that animated them.

It had taken weeks, and the first time she had Changed, it had been so blindingly painful that she’d vomited and passed out. When she’d woken, she’d been lying on one of the moldering chaises in the Dark Sisters’ rooms, a damp towel being sponged across her face. Mrs. Black had been leaning down over her, her breath as bitter as vinegar, her eyes alight. “You did well today, Theresa,” she had said. “Very well.”

That evening when Tessa had gone up to her room, there had been gifts for her, two new books on her bedside table. Somehow the Dark Sisters had realized that reading and novels were Tessa’s passion. There was a copy of Great Expectations and—of all things—Little Women. Tessa had hugged the books to herself and, alone and unwatched in her room, had let herself cry.

It had grown easier since then, the Changing. Tessa still didn’t understand what happened inside her to make it possible, but she had memorized the series of steps the Dark Sisters had taught her, the way a blind person might memorize the number of paces it takes to walk from their bed to the door of their room. She didn’t know what was around her in the strange dark place they asked her to journey to, but she knew the pathway through it.

She drew on those memories now, tightening her grip on the ragged bit of pink fabric she held. She opened her mind and let the darkness come down, let the connection that bound her to the hair ribbon and the spirit inside it—the ghostly echo of the person who had once owned it—unravel like a golden thread leading through the shadows. The room she was in, the oppressive heat, the noisy breathing of the Dark Sisters, all of it fell away as she followed the thread, as the light grew more intense around her and she wrapped herself in it as if she were wrapping herself in a blanket.

Her skin began to tingle and to sting with thousands of tiny shocks. This had been the worst part, once—the part that had convinced her she was dying. Now she was used to it, and bore it stoically as she shuddered all over, from her scalp to her toes. The clockwork angel around her throat seemed to tick faster, as if in rhythm with her speeding heart. The pressure inside her skin built—Tessa gasped—and her eyes, which had been closed, flew open as the sensation built to a crescendo—and then vanished.

It was over.

Tessa blinked dizzily. The first moment after a Change was always like blinking water out of your eyes after submerging yourself in a bath. She looked down at herself. Her new body was slight, almost frail, and the fabric of her dress hung loose, pooling on the floor at her feet. Her hands, clasped in front of her, were pale and thin, with chapped tips and bitten nails. Unfamiliar, alien hands.

“What is your name?” Mrs. Black demanded. She had risen to her feet and was looking down at Tessa with her pale eyes burning. She looked almost hungry.

Tessa didn’t have to answer. The girl whose skin she wore answered for her, speaking through her the way spirits were said to speak through their mediums—but Tessa hated to think about it that way; the Change was so much more intimate, so much more frightening, than that. “Emma,” the voice that came from Tessa said. “Miss Emma Bayliss, ma’am.”

“And who are you, Emma Bayliss?”

The voice replied, words tumbling out of Tessa’s mouth, bringing strong images with them. Born in Cheapside, Emma had been one of six children. Her father was dead, and her mother sold peppermint water from a cart in the East End. Emma had learned to sew to bring in money when she was still a small child. Nights, she spent sitting at the little table in her kitchen, sewing seams by the light of a tallow candle. Sometimes, when the candle burned down and there was no money for another, she would go out into the streets and sit below one of the municipal gas lamps, using its light to sew by… .

“Is that what you were doing out on the street the night you died, Emma Bayliss?” asked Mrs. Dark. She was smiling thinly now, running her tongue over her lower lip, as if she could sense what the answer would be.

Tessa saw narrow, shadowy streets, wrapped in thick fog, a silver needle working by faint yellow gaslight. A step, muffled in the fog. Hands that reached out of the shadows and took hold of her shoulders, hands that dragged her, screaming, into the darkness. The needle and thread falling from her hands, the bows ripped from her hair as she struggled. A harsh voice shouting something angry. And then the silver blade of a knife flashing down through the dark, slicing into her skin, drawing out the blood. Pain that was like fire, and terror like nothing else she’d ever known. She kicked out at the man holding her, succeeding in knocking the dagger from his hand; she caught the blade and ran, stumbling as she weakened, the blood draining out of her fast, so fast. She crumpled in an alley, hearing the hissing scream of something behind her. She knew it was following her, and she was hoping to die before it reached her—

The Change shattered like glass. With a cry Tessa fell to her knees, the torn little bow falling from her hand. It was her hand again—Emma had gone, like a cast-off skin. Tessa was once more alone inside her own mind.

Mrs. Black’s voice came from far away. “Theresa? Where is Emma?”

“She’s dead,” Tessa whispered. “She died in an alley—bled to death.”

“Good.” Mrs. Dark exhaled, a sound of satisfaction. “Well done, Theresa. That was very good.”

Tessa said nothing. The front of her dress was splotched with blood, but there was no pain. She knew it was not her blood; it wasn’t the first time this had happened. She closed her eyes, spinning in the darkness, willing herself not to faint.

“We should have had her do this before,” said Mrs. Black. “The matter of the Bayliss girl has been bothering me.”

Mrs. Dark’s reply was curt. “I wasn’t sure she was up to it. You remember what happened with the Adams woman.”

Tessa knew immediately what they were talking about. Weeks ago she had Changed into a woman who had died of a gunshot wound to the heart; blood had poured down her dress and she had Changed back immediately, screaming in hysterical terror until the Sisters had made her see that she herself was unharmed.

“She’s advanced wonderfully since then, don’t you think, Sister?” Mrs. Black said. “Given what we had to work with in the beginning—she didn’t even know what she was.”

“Indeed, she was absolutely unformed clay,” Mrs. Dark agreed. “We have truly worked a miracle here. I can’t see how the Magister could fail to be pleased.”

Mrs. Black gave a little gasp. “Does that mean—Do you think it’s time?”

“Oh, absolutely, my dear sister. She’s as ready as she’ll ever be. It’s time for our Theresa to meet her master.” There was a gloating note in Mrs. Dark’s voice, a sound so unpleasant that it cut through Tessa’s blinding dizziness. What were they talking about? Who was the Magister? She watched through lowered eyelashes as Mrs. Dark jerked the silk bellpull that would summon Miranda to come and take Tessa back to her room. It appeared that the lesson was over for today.

“Perhaps tomorrow,” Mrs. Black said, “or even tonight. If we told the Magister she was ready, I cannot imagine he would not hurry here without delay.”

Mrs. Dark, stepping out from behind the desk, chuckled. “I understand that you’re eager to be paid for all our work, dear sister. But Theresa must not be simply ready. She must be … presentable as well as able. Don’t you agree?”

Mrs. Black, following her sister, muttered a response that was cut short as the door opened and Miranda came in. She wore the same dull look as ever. The sight of Tessa crouched and bloody on the floor seemed to occasion no surprise in her. Then again, Tessa thought, she had probably seen far worse in this room.

“Take the girl back up to her room, Miranda.” The eagerness was gone from Mrs. Black’s voice, and she was all brusqueness again. “Get the things—you know, the ones we showed you—and get her dressed and ready.”

“The things … you showed me?” Miranda sounded blank.

Mrs. Dark and Mrs. Black exchanged a disgusted look, and approached Miranda, blocking Tessa’s view of the girl. Tessa heard them whispering to her, and caught a few words—“dresses” and “wardrobe room” and “do what you can to make her look pretty,” and then finally, Tessa heard the rather cruel, “I’m not sure Miranda is clever enough to obey vague instructions of that sort, sister.”