He passed it to her. Grace felt its weight in her hands, not quite sure what she was looking for. If she were an ordinary Shadowhunter, she would have handled plenty of steles, but Tatiana had always disapproved of her studying or training.

Christopher blinked his unusual violet eyes. “Just because it looks like a stele doesn’t mean anything—especially if its purpose was meant to be disguised for some reason.”

“Hold out your arm,” Grace said impulsively.

Christopher pushed up his shirtsleeve, revealing a Mark on his inside left forearm. Craft, maybe? Or Technique? “Go ahead if you like,” he said. “Draw something.”

She touched the tip of the pithos to his skin and hesitated, suddenly unsure of herself. She momentarily wished she had used her powers on him; she was sorely in need of the confidence they would bring her. Slowly and awkwardly, she drew the enkeli rune, the rune most Shadowhunters learned to draw first. Angelic power.

To her amazement, the moment it was finished, it disappeared from Christopher’s arm.

“Odd, isn’t it?” Christopher examined his arm; he’d clearly tried this already. “You draw a rune and it vanishes.”

“This Creation rune here on your arm,” she said. “Are you terribly fond of it?”

“No, not really—”

Grace took the pithos and, with the tip, traced the Creation rune on Christopher’s arm. He watched her with interest, and then some surprise as the Creation rune shimmered—and vanished.

Christopher’s eyebrows shot up into his hair. “What ho,” he said, sounding pleased. “Try to draw it on me again now.”

But that wasn’t what Grace had in mind. Experimentally, she touched the tip of the pithos to her own wrist—only to see the Creation rune leap into existence there, stark and black against her skin.

“Blimey,” Christopher said. “So it can move runes from one person to another? I wonder if that’s the purpose of it, or just one of its powers?”

“You don’t seem that surprised,” Grace observed.

“On the contrary. I’ve never heard of transferring a rune between Shadowhunters—”

“No, I meant—” Grace wished she hadn’t said anything. “I only meant that you didn’t seem surprised to see me put a rune on myself.”

“Why would I be?” Christopher asked, obviously confused. “You’re a Shadowhunter. It’s what we do.”

Grace’s heart sank. Now Christopher probably thought she was completely peculiar—and for some reason, that bothered her.

But Christopher was focused on the pithos in her hands. “How might it work, I wonder?”

Grateful that the subject had been dropped, Grace handed it back to him. “All we know so far is that it can move runes from one person to another, right?”

“Indeed, but why? And just as importantly, how? Runes can’t be contained in any metal, or any substance at all, that I am aware of. So is it sending the rune to another dimension for storage, and then bringing it back? Like a miniature rune-focused Portal?”

“A … rune-storage dimension?” Grace said doubtfully. “That seems unlikely.”

Christopher gave her a sheepish grin. “I’m still in the early hypothesizing phase of my investigation.” He gestured excitedly as he talked, his hands—covered in stains and burns and scars—slicing the air. “Different substances have different properties—density, for instance, or flammability, or dozens of other things. Magical things are no exception. As an example, I have been trying to determine what adamas is made of. All things in the world are made up of elements—like iron and oxygen and chlorine and so on—and there are only a discrete number of them. Yet adamas is not one of them. Surely it has magical properties separate from its physical makeup, but—” Suddenly he stopped, looking stricken. “I’m sorry, Grace, this must be tremendously boring for you.”

Grace gathered that boredom was the reaction Christopher was accustomed to from most people. But Grace wasn’t bored, not in the least. She wished he would keep talking. But Christopher was looking at her expectantly. If there was one thing she couldn’t bear, it was other people having expectations. She would always disappoint them. “I—no, but you see, I was hoping to find some activated moth-wing powder.”

The light in Christopher’s eyes dimmed. Clearing his throat, he set the pithos on the worktable. “We only have the unactivated sort,” he said in a businesslike tone, “but we could activate it here, I suppose.”

Make him, a little voice whispered inside her, the same voice that had guided her to force all kinds of people to do her bidding.

“There’s no need for that,” she said, instead, staring down at her hands. “I can manage it myself.”

“Very well,” Christopher said. “I am in your debt for helping me discover this device’s purpose, and happy to oblige. I’ll get the powder for you, and then would you mind going back out the way you came? I’d let you out properly, but I rarely use the front door.”

Hypatia Vex’s magic shop was in a large, one-story brick building between a shipping concern and a damp little restaurant serving coffee and sandwiches to a clientele of longshoremen. The exterior of the shop resembled a small, disused factory; mundanes passing by along the Limehouse street would see only a padlocked door with brass letters above it, small windows filmed with dirt and grime.

Lucie knew that long ago, the place had been a curiosity shop owned by a faerie named Sallows. It had fallen into disuse after his death, but now the floors had been sanded and given a fresh coat of wax, and the walls were painted in scarlet and blue. A series of floor-to-ceiling shelves were already filled with merchandise, and a long display case served as the shop counter. Behind it stood Hypatia, dressed in a flowing purple gown with black silk frog closures. She had a pair of small spectacles perched on the bridge of her nose and was going through a stack of bills and invoices, muttering under her breath.

Anna and Ariadne had already arrived—Anna was leaning against the counter, examining her gloves as if searching for a flaw in the leather. Ariadne, dressed in gear, was looking in fascination at a dollhouse on one of the shelves in which small, living dolls—faeries, perhaps?—darted from room to room, playing tiny musical instruments and sleeping in Lilliputian beds.

“Lucie,” Anna said, looking up with a smile. “I was beginning to wonder if you’d read my note.”

“I did—only I was a bit delayed at the Shadow Market,” said Lucie.

“What an exciting life you do lead,” Anna said. “Now, mind your manners. Hypatia thinks the workmen have been cheating her, and she isn’t in a good mood.”

“I can hear you,” Hypatia snapped, scowling. “Never hire gnome workmen, Herondale. They will overcharge you for lumber.”

Being overcharged for lumber was not the sort of thing that happened to heroines in books. Lucie sighed inwardly—she’d hoped that by the time she’d gotten there, Anna would have charmed Hypatia into a good mood. Clearly, that hadn’t happened. She hesitated, wondering how much she should say. Anna knew more than Ariadne about what Lucie and the others had been up to, but neither girl had any idea of the true purpose of Lucie’s mission.