Just then a sharp knock sounded on Miss Ackerbee’s door, making Tess jump.

“Come in, Rebecca,” Miss Ackerbee called.

“Tess’s things are ready,” said Rebecca, coming in and closing the door behind her. “Wilf gave me a hand with the lab bits and pieces.”

“And you told her Tess has to go into quarantine?”

“Hang on a minute,” Tess said before Rebecca had a chance to answer. “Quarantine?”

“It’s what we’re going to tell the other girls when they ask where you’ve gone,” Miss Ackerbee replied. She raised an eyebrow. “I’m sure not all of them will believe that you’ve been stricken with an infectious disease, but we’ll have to hope for the best.”

Tess sank into her chair, feeling like her chest was folding in on top of itself. She stared at the blanket on Miss Ackerbee’s desk, wondering how on earth she’d gone from conducting experiments on seaweed to being told she was some sort of monster, all in one morning. She felt like a stranger in her own skin, but in another way she felt as though she finally had some of the answers she’d needed all her life.

“You can have it, Tess, if you want it,” said Miss Ackerbee in a soft voice. Tess glanced up at her. “The blanket. It’s yours, after all.”

Tess lifted it into her arms as though it still contained her baby self, and a fold of it fell open to reveal a name tag stitched carefully against a seam.

“Teresita Mariana de Sousa,” she read, her eyes filling with tears again. “My name.”

“It’s how we knew what to call you,” said Miss Ackerbee, her own voice thickening. “I wondered if your mother made it for you. It looks as though she might have.”

“In another world?” whispered Tess, looking up at her housemistress. Two fat tears finally spilled out, pooling a little in her glasses before trickling to her chin.

“That’s my belief, yes,” said Miss Ackerbee, straightening her shoulders and sniffing, just once. Her eyes were shining.

“It’s almost one o’clock, Miss Ackerbee,” said Rebecca, behind Tess. “If we’re to get her going…” Her words trailed off as a cloud fell over Miss Ackerbee’s face. The housemistress nodded and got to her feet.

“Tess,” she said, bending over her desk and leaning heavily on the flat of her palms. “You’ve got to leave the house now, I’m afraid. Just for a short time, we hope—until this Cleat person can be satisfied with going away empty-handed. But as soon as we can, we’ll come to fetch you home.”

“Hang on—what? Where am I going?” Tess clutched the blanket tightly to herself.

“To my sister’s house, in the country,” said Rebecca, coming to stand beside Tess’s chair. She knelt, folding her hands in her lap, and looked up at Tess sympathetically. “Nobody knows about its connection to this house. So you should be safe there for a while. And I’ll stay with you all the time.”

“But—wait.” Tess closed her eyes. She put the blanket carefully in her lap and took her glasses off, rubbing her damp eyes with the heel of one hand. “Just wait a minute.”

“Tess, time is really against us…,” Miss Ackerbee began, her voice low and anxious.

“Miss Ackerbee—please. Why is this man—Mr. Cleat?—why is he coming for me? Why does he want me in particular?” She licked her lips, put her glasses back on and stared at Miss Ackerbee.

“What difference does it make?” said Rebecca. Tess turned to look at her. “He’s not having you, and that’s that.”

Tess turned back to the housemistress. “But there has to be a reason. How does he even know about me? If what you’re saying is true. If—if I’m not—if I’m not supposed to be here?” Tess struggled to find the words, but Miss Ackerbee knew what she meant.

“I can’t explain that, Tess. I truly don’t know. But as soon as I saw your name on his documents, I knew we had to keep you safe. We have to get you away from here.”

“But—” Tess began.

Miss Ackerbee leaned forward, her words urgent. She fixed Tess with a stare. “Your father left you here to save you from something. He must have had a good reason! If he brought you here, somehow, from another reality, hoping you’d find a loving home far away from the world you were born into, how can I possibly betray that by giving you up now?”

“But—just listen!” Tess scrunched her hands into fists, and Miss Ackerbee leaned back a little. “Mr. Cleat might be looking for me because he knows something about me—like, maybe, about these things I can do, the things you’ve been telling me about?”

“Well, yes. Of course. I can’t think of any other reason,” said the housemistress, sinking back into her chair. She frowned slightly as she looked at Tess. “He claimed he was related to you, but I don’t see how that’s possible. Plus,” she continued, her face hardening, “he didn’t seem like the type of person I’d trust to care for a dog, let alone a child.”

“But don’t you see? If he knows something about me,” Tess persisted, “I have to go with him, not run away.”

“What?” Rebecca got to her feet in a hurry. “Go with him? What sort of scheme is that?”

“But if he knows something about me, Miss Ackerbee, maybe he can tell me who I am? Where I came from?” Tess swallowed a lump in her throat. “Where my parents are?”

“There has to be another way, Tess,” Miss Ackerbee said, her eyes dull with sorrow.

“But there isn’t, is there?” Tess replied. “It’s been twelve years and this is the first time there’s been any hint that anyone outside of this house has ever even heard of me. This might be my only chance.”

A long moment of silence passed. “It’s a risky strategy,” said Miss Ackerbee finally, her steady gaze on Tess’s face. “I don’t like the idea of you being all alone, trying to figure things out by yourself while this man holds all the cards.”

“He doesn’t hold all the cards.” Tess sank her fingers into the blanket. “You’ve told me as much about me as you can. He doesn’t know I know. That gives me a card or two, doesn’t it?”

Miss Ackerbee smiled. “I’d say it gives you a royal flush,” she said.

“So—am I hearing right?” said Rebecca, putting her hands on her hips and striding away from Tess across the room. “Are you proposing we send one of our charges into goodness knows what sort of danger? This isn’t right, Aurelia.” She cut a glance at Tess and cleared her throat. “I mean, Miss Ackerbee.”

Miss Ackerbee leaned across her desk and took a sheet of notepaper in her hand. Quickly, in her neat writing, she printed a telephone number. “Take this,” she told Tess, handing her the paper, “and keep it somewhere about yourself, always. It’s the number for this house. If you need me, you get to a telephone and ask the operator to connect you here. Simply say the word quicksilver and I will know you need help. Do you understand?”

“Quicksilver,” Tess repeated. “Atomic number eighty. Atomic symbol Hg.” She blinked, looking up at Miss Ackerbee. “I won’t forget.”

“I know,” Miss Ackerbee said, capping her fountain pen. She got to her feet. “Right. Why don’t you go and finish packing, Tess, and we’ll wait here for Mr. Cleat. You can meet him yourself, and if your instinct tells you not to go with him, I will fight with everything I have to keep you here. If, however, you wish to leave, you may go with my blessing and I will be waiting here for you until you return.”

“This is lunacy,” Rebecca muttered. She turned away from Tess to face the corner of the room. “Utter madness.”

“I’m sorry, my dear,” Miss Ackerbee said, her words soft. “I hate to go against you like this, but I have to admit that I agree with Tess. This is her chance to find the answers neither you nor I can give her—answers she’s entitled to. Anyway, she can always come home once”—she paused, swallowing hard—“once it’s all over. We’ll find a way.”

Tess saw Rebecca shaking her head, but she didn’t say anything else.

“Thank you, Miss Ackerbee,” said Tess, getting to her feet. The hair on top of her head sat up and Tess glanced at her own forehead. “Violet says thanks too.”

“The best way to thank me is to come home safe—both of you,” Miss Ackerbee replied. “And you’re to write to me every single week, without fail. I shall miss you terribly.” She turned away quickly, as if to busy herself with putting away some documents, and Tess felt Rebecca’s hand on her shoulder. She allowed herself to be led out of the room, feeling like her ears were stuffed with cotton and her heart was a banging gong.