She stepped inside—and jumped. There was Christopher Lightwood, perched in the corner on a wooden stool, turning a peculiar object over in his hand. What is he doing hiding in a corner? she thought furiously. Couldn’t he sit at the table like a normal person, where she could have spied on him properly?

She smiled, opening her mouth to lie—she was on an errand for Charles, he’d left something in his old room—when Christopher turned and blinked at her.

“Oh! It’s you,” Christopher said with his usual sunny smile. “I thought it might be rats again. Hullo, Grace.”

“It’s awfully late,” she said conversationally, as if she ran into young men in cellars every day. “Do the Fairchilds know you’re here?”

“Oh, I’m here all the time,” he said, holding the peculiar object up to the light. It looked like a strange stele. “Henry’s got loads of equipment, and he doesn’t mind if I use it.”

“But—aren’t you going to ask me what I’m doing here?” Grace asked, approaching the worktable.

“Why would I do that?” Christopher seemed genuinely puzzled. “You’re affianced to Charles—surely you have a right to be here.”

She cleared her throat. “It’s a surprise for Charles. Could I convince you to take pity on me and help me find a particular ingredient?”

Christopher slid off the stool. “You’re working on a scientific surprise for Charles? I never thought he had much interest in science.” He set his odd stele down on the workbench. “Would you like a quick tour of the laboratory? I daresay it’s the best-equipped scientific workshop in London.”

Grace was nonplussed. She hadn’t compelled him to offer her the tour; he’d come up with that on his own. She could have reduced him to a babbling lump, she thought, saying things like I would die in order to help you with anything you could possibly desire, his eyes crossed with longing. But as Christopher seemed honestly chuffed at the chance to show off his beakers and tubes and vials, she found herself holding back.

She didn’t like using the power, really, she thought, as he led her to a series of shelves containing tiny jars full of colorful substances and started telling her about a table of chemical elements invented by a scientist in Russia a number of years earlier. Using it made her feel tied to her mother. To the darkness her mother served.

As she studied the contents of the little jars, Christopher told her about the way magic and science could be combined to create something entirely new. She didn’t quite follow, but she surprised herself by wanting to know more as he talked about the purpose of various objects and instruments, the experiments he and Henry conducted, the things they discovered.