Malcolm Fade waved a hand over his own cup. Purple sparks woke and danced in his glass. The red wine stain on the carpet unfurled like a flower and turned to purple smoke. Hypatia looked at the broken flute as if it had turned into a rat.

“I was a child in Cornwall long ago, where Atropa belladonna grows wild,” said Malcolm quietly. “I am an expert in the uses of deadly nightshade, and I have seen its cousin deadly nightsea before. Miss Carstairs is right. She has saved our lives.”

“Seize the mermaid,” Hypatia said between her teeth.

Anna was already up and out of her chair, dagger in hand, her movements light as a cat’s. Arabella was fumbling in her bodice, her teeth bared, but Anna caught at her wrist, twisting it hard. An item fell from Arabella’s fingers and rolled upon the golden carpet: it was the horn of a sea creature, sharpened to a deadly point.

“Let me end my life,” Arabella hissed, writhing, but Anna continued to hold her prisoner with an arm about her neck. Runes flared along Anna’s bare, slender arm; the dagger in her other hand glimmered like diamonds. “Let me die with honor as sea people do.”

“Honor? There is no honor in poison. It is a coward’s trick,” said Hypatia. “You intended to poison me and Malcolm Fade. And to what end? What power do you seek?”

“She seeks revenge,” said Malcolm. “I have heard of you, Arabella. You considered yourself insulted by the Nephilim years ago. It must have been a much greater matter than any of us realized, for when Hypatia told you they were here tonight you sought to pay them back.” His eyes narrowed. “Hypatia and I would have been dead—warlocks poisoned by Shadowhunters, you would claim. Every Downworlder in London would have been after Nephilim blood.”

Her face like stone, Hypatia picked up a small golden bell and shook it; the ringing echoed through the room. A blue-skinned faerie girl with foxgloves in her hair popped her head in through the door. “You rang, mistress?”

Hypatia’s mouth was a tight line. “Hyacinth. Have the guards take this mermaid away and put her in the wine cellar.”

“Please reconsider putting a poisoner in the wine cellar,” said Matthew. “I beg of you, for the sake of my future visits.”

Hypatia waved a hand. “Put her in the Whispering Room, then. She shouldn’t be able to cause any trouble there; we’ll take her to the Spiral Labyrinth shortly.”

“And then?” said Cordelia as two trolls wearing coats with gold braid entered, detached Arabella from Anna’s grip, and escorted the hissing mermaid out of the room. “What happens to her?”

“A trial,” said Hypatia. “A Downworlder matter of no interest to you. It will be fair. Downworlders are always fair.”