Christopher’s brass goggles were pushed up into his hair; he wore a shirt and trousers that had been burned and stained so many times he had been forbidden to wear them outside. Matthew could have been his mirror opposite: in blue-and-gold waistcoat and matching spats, he stood well away from the flames of the Bunsen burners, which had been turned up so high that the room was the temperature of a tropical island. Oscar napped gently at his feet.

“What’s going on, Kit?” said James. “Testing to see the temperature at which Shadowhunters melt?”

“My hair is certainly ruined,” said Matthew, pushing his hands through the sweat-darkened strands. “I believe Christopher is hard at work on the antidote. I am assisting by providing witty observations and trenchant commentary.”

“I’d rather you handed me that beaker,” said Christopher, pointing. Matthew shook his head. James grabbed the beaker and passed it to Christopher, who added a few drops of its contents to the liquid simmering in a retort by his elbow. He frowned. “It’s not going well, I’m afraid. Without this one ingredient, it doesn’t seem likely to work.”

“What ingredient?” James asked.

“Malos root, a rare plant. Shadowhunters aren’t supposed to cultivate it because doing so violates the Accords. I have been searching, and I asked Anna to try to get me some in Downworld, but we’ve had no luck.”

“Why would anyone be forbidden from growing some silly plant?” said Matthew.

“This plant only grows in soil that has been soaked by the blood of murdered mundanes,” said Christopher.

“I stand corrected,” Matthew admitted. “Ugh.”

“Dark magic plants, is it?” James’s eyes narrowed. “Christopher—can you draw me a sketch of the root?”

“Certainly,” said Christopher, as if this were not at all an odd request. He took a notebook from the inside pocket of his jacket and began to scribble on the back. The liquid in the retort had begun to turn black. James eyed it warily.

“There were some forbidden plants growing in Tatiana’s greenhouse,” James explained. “I told Charles about it at the time, and he didn’t seem to feel they were of great concern, but—”

Christopher held up the sketch, of an almost tulip-like plant with sharp-edged white leaves and a black root.

“Yes,” James said, his excitement rising. “I remember those—they were in the greenhouse at Chiswick. They struck me because those leaves looked like knives. We could go there now—is there a carriage free?”

“Yes.” Matthew’s excitement matched James’s own. “Charles had some sort of meeting, but he left the second carriage in the mews. Put your goggles down, Christopher—time for some fieldwork.”

Christopher grumbled slightly. “All right, all right—but I have to go change. I’m not allowed out in these clothes.”