Tessa saw Jem lean in and whisper something to Will, whose mouth quirked up at the corner in a smile. “Indeed,” Will said. “How could anyone despise us when we are so charming?”

“I am sure you know that you are not loved by most Downworlders.”

“But we thought de Quincey was an ally.” Charlotte rested her thin nervous hands on the back of one of the velvet chairs. “He has always cooperated with the Clave.”

“Pretense. It is in his interest to cooperate with you, so he does. But he would happily see you all sunk fathoms below the sea.”

Charlotte had gone pale, but rallied. “And you know nothing of his involvement with two women called the Dark Sisters? Nothing of his interest in automatons—mechanical creatures?”

“Ugh, the Dark Sisters.” Lady Belcourt shuddered. “Such ugly, unpleasant creatures. Warlocks, I believe. I avoided them. They were known to provide for the members of the club who might have less … savory interests. Demon drugs, Downworld prostitutes, that sort of thing.”

“And the automatons?”

Lady Belcourt fluttered her delicate hands in a bored fashion. “If de Quincey has some fascination with watch parts, I know nothing of it. In fact, when you first contacted me about de Quincey, Charlotte, I had no intention of coming forward with any information at all. It is one thing to share a few Downworld secrets with the Clave, another thing entirely to betray the most powerful vampire in London. That was, until I heard about your little shape-shifter.” Her green eyes came to rest on Tessa. The red lips smiled. “I can see the family resemblance.”

Tessa stared. “The resemblance to whom?”

“Why, to Nathaniel, of course. To your brother.”

Tessa felt as if ice water had been dumped down the back of her neck, shocking her to full alertness. “You’ve seen my brother?”

Lady Belcourt smiled, the smile of a woman who knows she holds a room in the palm of her hand. “I saw him a few times at various Pandemonium Club occasions,” she said. “He had that hapless look about him, poor creature, of a mundane under a spell. Probably gambled away everything he had. They always do. Charlotte told me the Dark Sisters took him; that doesn’t surprise me. They love to drive a mundane into the ground with debt and then collect in the most shocking ways… .”

“But he’s alive?” Tessa said. “You’ve seen him alive?”

“It was some time ago, but yes.” Lady Belcourt gave a wave of her hand. Her gloves were scarlet, and her hands looked as if they had been dipped in blood. “To return to the matter at hand,” she said. “We were speaking of de Quincey. Tell me, Charlotte, did you know he holds parties at his town house in Carleton Square?”

Charlotte took her hands off the chair back. “I’ve heard it mentioned.”

“Unfortunately,” said Will, “it seems he neglected to invite us. Perhaps our invitations went astray in the post.”

“At these parties,” Lady Belcourt went on, “humans are tortured and killed. I believe their bodies are dumped into the Thames for the mudlarks to pick over. Now, did you know that?”

Even Will looked taken aback. Charlotte said, “But the murder of humans by the Night Children is forbidden under the Law—”

“And de Quincey despises the Law. He does this as much to mock the Nephilim as because he enjoys the killing. Though he does enjoy that, make no mistake about it.”

Charlotte’s lips were bloodless. “How long has this been going on, Camille?”

So that was her name, Tessa thought. Camille. It was a French-sounding name; perhaps that explained her accent.

“At least a year. Perhaps longer.” The vampire’s tone was cool, indifferent.

“And you are telling me this only now because …” Charlotte sounded hurt.

“The price for revealing the secrets of the Lord of London is death,” Camille said, her green eyes darkening. “And it would have done you no good, even if I had told you. De Quincey is one of your allies. You have no reason and no excuse to burst into his home as if he were a common criminal. Not with no evidence of wrongdoing on his part. My understanding is that, under these new Accords, a vampire must actually be observed harming a human before the Nephilim can take action?”

“Yes,” said Charlotte reluctantly, “but if we had been able to attend one of the parties—”

Camille let out a short laugh. “De Quincey would never let that happen! At the first sight of a Shadowhunter, he would have locked the place up tightly. You would never have been permitted to enter.”

“But you could,” Charlotte said. “You could have brought one of us with you—”

The plume on Camille’s hat trembled as she tossed her head. “And risk my own life?”

“Well, you’re not precisely alive, are you?” said Will.

“I value my existence as much as you do, Shadowhunter,” said Lady Belcourt, narrowing her eyes. “A lesson you would do well to learn. It could hardly hurt the Nephilim to cease thinking that all those who do not live exactly as they do must therefore not truly live at all.”

It was Jem who spoke then, for what seemed like the first time since they had entered the room. “Lady Belcourt—if you’ll pardon my asking—what is it exactly that you want from Tessa?”

Camille looked directly at Tessa then, her green eyes as brilliant as jewels. “You can disguise yourself as anyone, is that correct? A perfect disguise—appearance, voice, and manner? That’s what I have heard.” Her lip curled. “I have my sources.”

“Yes,” Tessa said hesitantly. “That is, I have been told the disguise is identical.”

Camille looked at her narrowly. “It would have to be perfect. If you were to disguise yourself as me—”

“As you?” Charlotte said. “Lady Belcourt, I don’t see—”

“I see,” said Will immediately. “If Tessa were disguised as Lady Belcourt, she could make her way into one of de Quincey’s parties. She could observe him breaking the Law. Then the Clave could attack, without shattering the Accords.”

“Quite the little strategist, you are.” Camille smiled, revealing her white teeth once again.

“And it would also provide a perfect opportunity to search de Quincey’s residence,” said Jem. “See what we can discover about his interest in these automatons. If he really has been murdering mundanes, there’s no reason to think that it wasn’t for more purposes than mere sport.” He gave Charlotte a meaningful look, and Tessa knew that he was thinking, as she was, of the bodies in the cellar of the Dark House.

“We would have to figure out some way to signal the Clave from inside de Quincey’s,” Will mused, his blue eyes already alight. “Perhaps Henry could devise something. It would be invaluable to have a blueprint of the house’s construction—”

“Will,” Tessa protested. “I don’t—”

“And of course you wouldn’t be going alone,” Will said impatiently. “I would go with you. I wouldn’t let anything happen to you.”

“Will, no,” Charlotte said. “You and Tessa alone, in a house full of vampires? I forbid it.”

“Then who would you send in with her, if not me?” Will demanded. “You know I can protect her, and you know I’m the right choice—”

“I could go. Or Henry—”

Camille, who had been watching all this with a look of mixed boredom and amusement, said, “I’m afraid I agree with William. The only individuals admitted to these parties are de Quincey’s close friends, vampires, and the human subjugates of vampires. De Quincey has seen Will before, passing as a mundane fascinated by the occult; he won’t be surprised to find that he’s graduated to vampiric servitude.”

Human subjugate. Tessa had read of them in the Codex: Subjugates, or darklings, were mundanes who had sworn themselves to the service of a vampire. For the vampire, they provided companionship and food, and in return received small transfusions of vampire blood at intervals. This blood kept them bound to their vampire master, and also ensured that when they died, they would become vampires as well.

“But Will is only seventeen,” Charlotte protested.

“Most human subjugates are young,” said Will. “Vampires like to acquire their subjugates when they’re youthful—prettier to look at, and less chance of diseased blood. And they’ll live a bit longer, though not much.” He looked pleased with himself. “Most of the rest of the Enclave wouldn’t be able to pass convincingly as a handsome young human subjugate—”

“Because the rest of us all are hideous, are we?” Jem inquired, looking amused. “Is that why I can’t do it?”

“No,” Will said. “You know why it can’t be you.” He said it without any inflection, and Jem, after looking at him for a moment, shrugged and looked away.

“I’m truly not sure about this,” Charlotte said. “When is the next of these events set to happen, Camille?”

“Saturday night.”

Charlotte took a deep breath. “I’ll have to speak to the Enclave, before I can agree. And Tessa would have to agree as well.”

Everyone looked at Tessa.

She licked her dry lips nervously. “You believe,” she said to Lady Belcourt, “that there’s a chance my brother might be there?”

“I cannot promise he will be there. He might. But someone there will likely know what has happened to him. The Dark Sisters were regulars at de Quincey’s parties; doubtless they or their cohorts, if captured and interrogated, will yield you some answers.”

Tessa’s stomach churned. “I’ll do it,” she said. “But I want to be promised that if Nate is there, we’ll get him out, and if he isn’t, we’ll find out where he is. I want to make sure it’s not all about catching de Quincey. It must be about saving Nate, too.”

“Of course,” Charlotte said. “But I don’t know, Tessa. It will be very dangerous—”

“Have you ever Changed yourself into a Downworlder?” Will inquired. “Do you even know if it’s something that would be possible?”

Tessa shook her head. “I’ve never done anything like that. But … I could try.” She turned to Lady Belcourt. “Could I have something of yours? A ring, or a handkerchief perhaps.”

Camille reached her hands behind her head, brushing aside the thick coils of silver-blond hair that lay against her neck, and unclasped her necklace. Letting it dangle from her slender fingers, she held it out to Tessa. “Here. Take this.”

With a frown Jem stepped forward to take the necklace, and then held it out to Tessa. She felt the weight of it as she took it from him. It was heavy, and the square ruby pendant the size of a bird’s egg felt cold to the touch, as cold as if it had been lying in snow. Closing her hand around it was like closing her fingers around a shard of ice. She took a sharp breath, and closed her eyes.