“Miss Gray,” she said. “I am Charlotte Branwell, head of the London Institute, and this beside me is Brother Enoch—”

“What kind of monster is he?” Tessa whispered.

Brother Enoch said nothing. He was entirely expressionless.

“I know there are monsters on this earth,” said Tessa. “You cannot tell me otherwise. I have seen them.”

“I would not want to tell you otherwise,” said Mrs. Branwell. “If the world were not full of monsters, there would be no need for Shadowhunters.”

Shadowhunter. What the Dark Sisters had called Will Herondale.

Will. “I was—Will was with me,” said Tessa, her voice shaking. “In the cellars. Will said—” She broke off and cringed inwardly. She should not have called Will by his Christian name; it implied an intimacy between them that did not exist. “Where is Mr. Herondale?”

“He’s here,” Mrs. Branwell said calmly. “In the Institute.”

“Did he bring me here as well?” Tessa whispered.

“Yes, but there is no need to look betrayed, Miss Gray. You had struck your head quite hard, and Will was concerned about you. Brother Enoch, though his looks might frighten you, is a skilled practitioner of medicine. He has determined that your head injury is slight, and in the main you are suffering from shock and nervous anxiety. In fact, it might be for the best if you sat down now. Hovering barefoot by the door like that will only give you a chill, and do you little good.”

“You mean because I can’t run,” Tessa said, licking her dry lips. “I can’t get away.”

“If you demand to get away, as you put it, after we have talked, I will let you go,” said Mrs. Branwell. “The Nephilim do not trap Downworlders under duress. The Accords forbid it.”

“The Accords?”

Mrs. Branwell hesitated, then turned to Brother Enoch and said something to him in a low voice. Much to Tessa’s relief, he drew up the hood of his parchment-colored robes, hiding his face. A moment later he was moving toward Tessa; she stepped back hurriedly and he opened the door, pausing only for a moment on the threshold.

In that moment, he spoke to Tessa. Or perhaps “spoke” was not the word for it: She heard his voice inside her head, rather than outside it. You are Eidolon, Theresa Gray. Shape-changer. But not of a sort that is familiar to me. There is no demon’s mark on you.

Shape-changer. He knew what she was. She stared at him, her heart pounding, as he went through the door and closed it behind him. Tessa knew somehow that if she were to run to the door and try the handle she would once again find it locked, but the urge to escape had left her. Her knees felt as if they had turned to water. She sank down in one of the large chairs by the bed.

“What is it?” Mrs. Branwell asked, moving to sit in the chair opposite Tessa’s. Her dress hung so loosely on her small frame, it was impossible to tell if she wore a corset beneath it, and the bones in her small wrists were like a child’s. “What did he say to you?”

Tessa shook her head, gripping her hands together in her lap so that Mrs. Branwell could not see her fingers trembling.

Mrs. Branwell looked at her keenly. “First,” she said, “please call me Charlotte, Miss Gray. Everyone in the Institute does. We Shadowhunters are not so formal as most.”

Tessa nodded, feeling her cheeks flush. It was hard to tell how old Charlotte was; she was so small that she looked quite young indeed, but her air of authority made her seem older, old enough that the idea of calling her by her Christian name seemed very odd. Still, as Aunt Harriet would have said, when in Rome …

“Charlotte,” Tessa said, experimentally.

With a smile, Mrs. Branwell—Charlotte—leaned back slightly in her chair, and Tessa saw with some surprise that she had dark tattoos. A woman with tattoos! Her marks were like the ones Will bore: visible on her wrists below the tight cuffs of her dress, with one like an eye on the back of her left hand. “Second, let me tell you what I already know about you, Theresa Gray.” She spoke in the same calm tone she’d had before, but her eyes, though still kind, were sharp as pins. “You’re American. You came here from New York City because you were following your brother, who had sent you a steamship ticket. His name is Nathaniel.”

Tessa sat frozen. “How do you know all this?”

“I know that Will found you in the Dark Sisters’ house,” Charlotte said. “I know that you claimed someone named the Magister was coming for you. I know that you have no idea who the Magister is. And I know that in a battle with the Dark Sisters, you were rendered unconscious and brought here.”

Charlotte’s words were like a key unlocking a door. Suddenly Tessa remembered. Remembered running with Will down the corridor; remembered the metal doors and the room full of blood on the other side; remembered Mrs. Black, her head severed; remembered Will flinging his knife—

“Mrs. Black,” she whispered.

“Dead,” said Charlotte. “Very.” She settled her shoulders against the back of the chair; she was so slight that the chair rose up high above her, as if she were a child sitting in a parent’s chair.

“And Mrs. Dark?”

“Gone. We searched the whole house, and the nearby area, but found no trace of her.”

“The whole house?” Tessa’s voice shook, very slightly. “And there was no one in it? No one else alive, or … or dead?”

“We did not find your brother, Miss Gray,” Charlotte said. Her tone was gentle. “Not in the house, nor in any of the surrounding buildings.”

“You—were looking for him?” Tessa was bewildered.

“We did not find him,” Charlotte said again. “But we did find your letters.”

“My letters?”

“The letters you wrote to your brother and never sent,” said Charlotte. “Folded under your mattress.”

“You read them?”

“We had to read them,” said Charlotte in the same gentle tone. “I apologize for that. It is not often that we bring a Downworlder into the Institute, or anyone who is not a Shadowhunter. It represents a great risk to us. We had to know that you were not a danger.”

Tessa turned her head to the side. There was something horribly violating about this stranger having read her inmost thoughts, all the dreams and hopes and fears she’d poured forth, not thinking anyone would ever see them. The backs of her eyes stung; tears were threatening, and she willed them back, furious with herself, with everything.

“You’re trying not to cry,” Charlotte said. “I know that when I do that myself, it sometimes helps to look at a bright light directly. Try the witchlight.”

Tessa moved her gaze to the stone in Charlotte’s hand and gazed at it fixedly. The glow of it swelled up in front of her eyes like an expanding sun. “So,” she said, fighting past the tightness in her throat, “you have decided I am not a danger, then?”

“Perhaps only to yourself,” said Charlotte. “A power such as yours, the power of shape-shifting—it is no wonder the Dark Sisters wanted to get their hands on you. Others will as well.”

“Like you do?” Tessa said. “Or are you going to pretend that you’ve let me into your precious Institute simply out of charity?”

A look of hurt flashed across Charlotte’s face. It was brief, but it was real, and it did more to convince Tessa that she might have been wrong about Charlotte than anything the other woman could have said. “It is not charity,” she said. “It is my vocation. Our vocation.”

Tessa simply looked at her blankly.

“Perhaps,” Charlotte said, “it would be better if I explained to you what we are—and what we do.”

“Nephilim,” said Tessa. “That’s what the Dark Sisters called Mr. Herondale.” She pointed at the dark markings on Charlotte’s hand. “You’re one as well, aren’t you? Is that why you have those—those markings?”

Charlotte nodded. “I am one of the Nephilim—the Shadowhunters. We are … a race, if you will, of people, people with special abilities. We are stronger and swifter than most humans. We are able to conceal ourselves with magics called glamours. And we are especially skilled at killing demons.”

“Demons. You mean—like Satan?”

“Demons are evil creatures. They travel great distances to come to this world and feed upon it. They would ravage it into ashes and destroy its inhabitants if we did not prevent it.” Her voice was intent. “As it is the job of the human police to protect the citizenry of this city from one another, it is our job to protect them from demons and other supernatural dangers. When there are crimes that affect the Shadow World, when the Law of our world is broken, we must investigate. We are bound by the Law, in fact, to make inquiries even into the rumor of Covenant Law being contravened. Will told you about the dead girl he found in the alley; she was the only body, but there have been other disappearances, dark rumors of mundane boys and girls vanishing off the city’s poorer streets. Using magic to murder human beings is against the Law, and therefore a matter for our jurisdiction.”

“Mr. Herondale seems awfully young to be a sort of policeman.”

“Shadowhunters grow up quickly, and Will did not investigate alone.” Charlotte didn’t sound as if she wished to elaborate. “That is not all we do. We safeguard the Covenant Law and uphold the Accords—the laws that govern peace among Downworlders.”

Will had used that word as well. “Downworld? Is that a place?”

“A Downworlder is a being—a person—who is part supernatural in origin. Vampires, werewolves, faeries, warlocks—they are all Downworlders.”

Tessa stared. Faeries were a children’s tale, and vampires the stuff of penny dreadfuls. “Those creatures exist?”

“You are a Downworlder,” Charlotte said. “Brother Enoch confirmed it. We simply don’t know of what sort. You see, the kind of magic you can do—your ability—it isn’t something an ordinary human being could do. Neither is it something one of us, a Shadowhunter, could do. Will thought you were most likely a warlock, which is what I would have guessed myself, but all warlocks have some attribute that marks them as warlocks. Wings, or hooves, or webbed toes, or, as you saw in the case of Mrs. Black, taloned hands. But you, you’re completely human in appearance. And it is clear from your letters that you know, or believe, both of your parents to be human.”

“Human?” Tessa stared. “Why wouldn’t they have been human?”

Before Charlotte could answer, the door opened, and a slender, dark-haired girl in a white cap and apron came in, carrying a tea tray, which she set down on the table between them. “Sophie,” Charlotte said, sounding relieved to see the girl. “Thank you. This is Miss Gray. She will be a guest of ours this evening.”

Sophie straightened, turned to Tessa, and bobbed a curtsy. “Miss,” she said, but the novelty of being curtsied to was lost on Tessa as Sophie raised her head and her full face became visible. She ought to have been very pretty—her eyes were a luminous dark hazel, her skin smooth, her lips soft and delicately shaped—but a thick, silvery ridged scar slashed from the left corner of her mouth to her temple, pulling her face sideways and distorting her features into a twisted mask. Tessa tried to hide the shock on her own face, but she could see as Sophie’s eyes darkened that it hadn’t worked.