“How impressive,” she said. “Tattle away, boy. I’ll tell the Clave Grace raised the demons herself. I’ll tell them she’s deep in black magic studies up to her pretty little ears. I’ll turn her loose and throw her back on their mercy with her reputation stained forever. I’ll ruin her life, if you want to play that game.” She jabbed a finger toward his chest. “You care, Herondale. That is your weakness.”

James stepped back in revulsion as Tatiana clambered into the trap. A moment later it was rattling off down the road, the ponies snorting and the reins jangling.

* * *

There was a long and awkward silence as the group of Shadowhunters watched the Blackthorn carriage vanish into the fog.

“Well,” said Alastair at last. “I think it’s time for Cordelia and I to be going.”

“I cannot go yet,” said Cordelia. She held out her arm and saw her brother’s eyes widen. A long, bloody cut ran from her elbow to her wrist. She had barely felt it during the battle, but it was beginning to sting. “I need a healing rune. If I return home like this, Mother will faint.”

“Several of us are wounded,” said Christopher. “Unless we want to explain what happened here, and it seems that would be a bad idea, we should probably apply iratzes.” He turned to Thomas. “I will do yours.”

“Please don’t,” said Thomas. Christopher did not always have the best of luck with runes.

“Oh, bloody hell, I’ll do it,” said Alastair, and stomped heavily over to Thomas’s side. Thomas watched in what seemed to be shock as Alastair produced a stele and began to draw on the bare skin of his arm where his shirt had been torn.

Beside Cordelia, Lucie produced her stele with a flourish. “Our first healing rune!” she announced, putting the tip of the stele to Cordelia’s wrist. “A historic moment for a pair of soon-to-be-famous parabatai.”

“I hate to seem ungrateful for the assistance,” said James. “But what on earth brought you all here? How did you know what was going to happen?”

“I heard about the Cerberus from Jess—Jessamine,” said Lucie, putting the finishing touches on Cordelia’s rune. They were both leaning against the low wall that ran along the Embankment. “Ghosts, they gossip.” She repeated for James the story she’d told the rest of them on the way to Chelsea, finishing with: “So, it seems the demon you killed in the greenhouse had time to multiply, and the new demons came looking for Grace when she left Chiswick.”

“There were certainly a lot of them,” said Cordelia. “Much worse than just the one in the greenhouse.”

“Perhaps they all had secret assignations with Grace,” said Lucie.

Alastair snorted. “That Blackthorn woman must be mad, letting Cerberus demons run wild in her shrubberies,” he said, putting his stele away. Thomas touched his own arm with a sort of wondering look; his wound was already beginning to close up. Alastair might be snappish, but he was handy with a stele.

James and Matthew had sat down on the ground so James could properly steady Matthew’s face with his hand. He drew an iratze lightly on his cheek while Matthew squirmed and complained. “It’s hard to say how much she knew,” James said. “I’m sure she was aware of the original demon in the greenhouse, but likely not its vengeful progeny.”

“She knew enough to come here,” Christopher pointed out. “Though she may just have been following Grace.”

James looked thoughtful; Cordelia could not help but wonder what Tatiana had said to him by the pony trap. He had looked stunned, as if she had hit him in the face.

“They disappeared because you told them to, didn’t they?” Cordelia said.

“So it seems.” James was examining Matthew’s cheek, apparently considering his rune work. Satisfied, he sat back. Matthew produced a flask from his pocket with a relieved air, unscrewed the top, and took a long drink. “They went back to whatever dimension Cerberus demons hail from. In the name of my grandfather.”

He sounded bitter.

“How nice for you to be related to such an important sort of demon,” said Alastair dryly.

“If it actually cared that James was related to an ‘important’ demon, it should have said something to me, too,” said Lucie. “I am his sister. I do not appreciate being overlooked.”

James smiled—which, Cordelia suspected, had been Lucie’s aim. He had a perfectly lethal dimple that flashed when he smiled. Such things should be illegal.

“They’re loyal to the Blackthorn family, in their horrid sort of way,” said Lucie thoughtfully. “That’s why they wanted us not to say anything about what happened tonight.”

“Ah,” said Alastair. “Because the Clave wouldn’t look too kindly on the Blackthorns breeding a pack of Cerberus demons and letting them chase after Herondale, even though he is very irritating.”

“I told you, Benedict Lightwood’s the one that bred them,” Lucie said crossly.

“Unpleasant as all that was,” Matthew said, “there is something comforting about fighting the ordinary kind of demon under cover of darkness, rather than poisonous ones that appear during the day.”

“Oh!” said Cordelia. “That reminds me. We should tell them what Hypatia said, Matthew. That we could speak to Ragnor Fell about the demons in the park.”

Everyone started to sputter questions. Matthew held up a hand. “Yes, we spoke to Hypatia Vex at the Hell Ruelle. She said she would send Ragnor a message. It is hardly a sure thing.”

“Perhaps, but Anna was right,” said Cordelia. “We must speak to more Downworlders regardless. There was much talk of Magnus Bane—”

“Ah, Magnus Bane,” said Matthew. “My personal hero.”

“Indeed, you once described him as ‘Oscar Wilde if he had magic powers,’ ” said James.

“Magnus Bane threw a party in Spain I attended,” said Thomas. “It was a little difficult, since I did not know a soul. I got rather drunk.”

Matthew lowered the flask with a grin. “Is that when you got your tattoo?”

Lucie clapped her hands. “The boys joke about the tattoo Thomas got in Spain, but Thomas will never let me see it. Isn’t that the meanest thing you ever heard, Cordelia? I am a writer. I believe I should have the experience of studying a tattoo at close quarters.”

“I believe you shouldn’t,” said Thomas, with conviction.

“Is the problem that it is in an unmentionable place?” asked Lucie.

“No, Lucie,” said Thomas, with a hunted air.

“I’d like to see it,” said Alastair, in a surprisingly quiet voice.

Thomas hesitated, then unbuttoned the shirtsleeve of his unwounded arm, and rolled it up to his elbow. Everyone leaned forward. Against the pale skin on the inside of Thomas’s muscular arm was a gray-and-black tracery of a compass. North, south, east, and west were delineated by blades like the points of daggers, and at the heart of the compass, unfurling dark petals, was a rose.

Cordelia had thought a tattoo would be rather more like their Marks, but it reminded her of something else instead. It was ink, the way books and poems were made of ink, telling a permanent story.

Lucy applauded. Alastair made an odd sort of noise. He was looking away, as if the sight of Thomas bothered him.

“I think it is lovely, Thomas,” Cordelia said. “North points up your arm, along the vein that runs to your heart.”

“So does that mean you’re close friends with Magnus Bane, Thomas?” said Lucie. “Can you reach out to him for help?”

“He never even made an appearance at the party,” said Thomas, rolling his sleeve down. “But reaching out to Ragnor Fell is a good idea.”

“As long as he will keep all this to himself,” said Christopher, pushing his spectacles up the bridge of his nose. “We cannot tell any Shadowhunters what happened here tonight. We all heard what that demon said.”

There was a murmur of assent, broken by Alastair. “Cordelia and I must depart,” he said. “As for your little secrets, you cannot trust demons. It does not matter what they claim.”

Cordelia knew that tone in his voice. “Alastair, you must promise to keep everything that happened here tonight to yourself.”

“Why should I promise?” Alastair demanded.

“Because even if demons are liars, the risk is too great,” said Cordelia, a little desperately. “The demon said it would target our families if any of us spoke of what happened tonight. Think of Mother and Father.”

Alastair looked mutinous.

“If you do not promise,” Cordelia added, “I will not go home with you. I will stay out all night and be utterly ruined. I will have to marry Thomas or Christopher.”

“What ho,” said Christopher, looking surprised. Thomas smiled.

“If you have any concern for our family, you must promise,” Cordelia said. “Please, Alastair.”

There was a murmur all around; Lucie looked worried. James was looking at Cordelia with an expression she could not decipher.

Alastair’s eyes narrowed. “Very well, I promise,” he muttered. “Now come away at once. We have much to discuss when we return home.”

* * *

It was nearing midnight when the five of them—Lucie, James, Matthew, Thomas, and Christopher—finally returned to the Institute. Lucie regarded the bright-lit windows curiously as they spilled into the courtyard. It was unusual at this hour for all the lamps to be on.

James lifted a finger to his lips before pushing open the wide front doors—they opened to the touch of any Shadowhunter’s hand—and led the way inside and up the stairs.

The first-floor hallway shimmered with witchlights. The door of the parlor stood open, and the sound of a Welsh song rang out into the corridor.

Nid wy’n gofyn bywyd moethus,

Aur y byd na’i berlau mân: