“At least you’ve kept your sense of humor,” Mallory said, expression tight with concentration. When they’d adjusted the bottles, she adjusted the mirror, then stood up again.

Catcher did the same. “This will detect alchemical resonance.”

Mallory nodded. “We’ve created the appropriate mix of salts and mercury, added the necessary symbology. We just have to quicken the magic. You ready?” she asked Jeff.

“Calibrating,” he said. “Nearly there.” With a final tap, he rolled his shoulders and moved to stand behind the machine, aiming the tablet at it. “Ready.”

“We’re going to do Wrigley first,” Catcher said. “We know where those symbols are, so it’ll be a good test.” At Mallory’s nod, he struck a match in the dark. The smell of sulfur singed the air. As Mallory closed her eyes to whisper quiet words, he dropped the match into the crucible.

There was a pop and the hiss of fire meeting fuel, and a pale beam of smoky light shot from the crucible, bounced off the mirror above it, and shot north. It faded as it moved away from us, and disappeared completely when a building interrupted our line of sight. Probably for the best—we didn’t need to field phone calls about laser beams over Chicago.

“Here,” Jeff said, and we gathered around him. He’d pulled up the three-dimensional map of the city. The light was green on the tablet, and it speared north from Cadogan House to Wrigleyville.

“Nice,” Mallory said, offering her husband a high five. But his gaze was stuck to the screen. The beam of light didn’t stop when it reached Wrigleyville. It flared and refracted, flying out on another trajectory until it stopped and flared again, hitting another hot spot.

And it didn’t stop. The light kept flaring, refracting, traveling again until the program had traced a dozen hot spots across the city. Nearly to Skokie to the north, nearly to Calumet City to the south, and from the lake to Hellriver in the west. There’d been more symbols in Hellriver, and we’d missed them, not that we’d known to look.

The hot spots and the line between them formed their own alchemical symbol—a circle inside a diamond inside a square, all of which was surrounded by another circle.

“There are so many of them,” Jeff said quietly.

Ethan stood silently and stoically beside me, concern flaring as he looked at what seemed an obvious threat to his city, his vampires.

“Holy Batman Jesus,” Mallory murmured, staring at the screen, then the city, then back again. Then she looked at me. “That’s why the code doesn’t make sense—even when we can translate the symbols. You read it in the round. A little bit from each hot spot, one hot spot after another, in order.”

I looked down at the symbol again, imagined reading one line of alchemy after another across the symbol before starting back at the beginning and reading through the second line.

“Oh,” I said. “Yes. That’s why the phrases seem contradictory. Because they are, at least within each block of text.” I looked back at Ethan. “If we can get images of all the hot spots, we can improve the odds of actually getting the thing translated.”

“Then we’ll make it happen,” he said. “What’s the significance of the symbol?”

“It’s called the Quinta Essentia,” Catcher said. “The square represents mankind. The inner circle represents earth. The outer circle is the universe, which represents the higher resonance. The diamond is the mechanism through which you reach the resonance.”

“Increasing the resonance,” Mallory said. “That’s got to be part of the equation.”

Catcher looked at her. “What are you thinking?”

“I don’t know,” she said. “Let me play it out.” She paced to the other end of the widow’s walk, looked over the city for a moment, arms crossed and cardigan pulled tight against the chilly breeze.

“Can you send a screenshot of the symbol to Gabriel?” I asked while she paced. “It might be the symbol Kane saw.”

Jeff nodded, looked down at the tablet. “On that.”

Mallory walked back to us. “The nullification part of the equation—that’s the part that’s been bothering me. I couldn’t figure out why the sorcerer would want to nullify something about himself. I hadn’t thought about what we know now—that the alchemy is intended to affect other people. And I think that’s true of the nullification term, too.”

“Who is it nullifying?” Catcher asked with a frown.

“Us. Our free will.”

We stared at her.

“I don’t understand,” Ethan said. “Even vampire glamour can’t conquer free will.”

“Not alone,” Mallory said. “But we aren’t talking about just a vampire.”

“We’re talking about a vampire and a sorcerer,” Catcher said, voice low and heavy with concern. “And they’re working in concert.”

“Exactly,” she said. “We’ll have to check this against the actual code, but what if the alchemy, I guess, twists the vampire’s glamour together with the sorcerer’s magic? Like, I don’t know, braiding steel cables together to make them stronger, or something.”

“And that’s where the nullification comes in,” Ethan said. “To boost the effect of their magic by eliminating our defenses.”

The mood went understandably morose. Who wouldn’t be worried about that? I thought of that moment on the train when the Rogue’s glamour had sought out the part of me that was soft and fragile as a nestling. It had been vulnerability stacked atop vulnerability. That exposure twisted and magnified was terrifying. Added to whatever warped activities he actually wanted us to do? Exponentially worse.

“All right,” Ethan said, the words piercing through the fear-laden magic that swirled with the winds across the roof. “There is no point in fear. That’s what Reed would prefer. We figure a way forward. And I am open to ideas.”

I couldn’t look away from the pulsing symbol that surrounded an enormous segment of the city. “I don’t know if ideas are going to help us.”

I felt Ethan’s gaze on me. “Sentinel?”

“Look at the symbol,” I said, looking back at them. “All the hot spots have been drawn. All the alchemy’s in place. He just has to kindle the magic.”