We went right past the morgue and down the hall into the ICU. He used air magic to disguise our presence from the nurses. It was creepy, being among all those sick people who didn’t know we were there.

We went into one room where an old woman was lying with her eyes closed and a tube down her throat. Con’s eyes were shining. I figured out what he wanted to do but it was already too late. “Con, she’s not dead.”

“Maybe that’s the key, though,” he said. “She’s nearly dead. Maybe you need to put the chaos in while there’s still a spark of life.”

“You have to leave her alone,” I said. “She’s alive.”

I kept saying it over and over as he pushed me aside and reached his hand out for her. Dark chaos spilled from his fingers. I saw the woman’s body jerk and tremble.

I felt something pinch inside my chest. I gasped and fell to my knees just as the old woman opened her eyes; they were blank but swirling with colors, like the eyes of Chaos-ridden animals. They fixed on me and somehow I thought she recognized me. Jericho, her eyes were saying. Jericho.

Constantine wasn’t relying on me just for energy, I realized. He was using pieces of my soul — using them as if they were batteries, shoving them into the Chaos-ridden, into this woman, like an electrical shock that would bring her back to life.

I didn’t see the woman die. I could hear Con exclaiming in annoyance that she was gone. Another failed experiment. All I could do was wonder how much of my soul was left now that my brother had shredded it.

Call put the book down. He was breathing so hard he was light-headed. The words on the page were like a slap in the face. He had known Constantine Madden as the Enemy of Death, the cause of his mother’s demise, the monster who the Assembly would rather keep their truce with for fear of starting the war over again, but still this was horrifying in a wholly different way. It was personal — what he’d done to his brother, ripping pieces off his soul. Constantine hadn’t done it to save someone he loved. He hadn’t killed that woman in desperation. He’d done it as an experiment. Just because he was curious. And cruel.

Constantine Madden hadn’t been driven to making terrible choices by grief. He’d been making terrible choices way before his brother died.

And while Master Joseph might have pushed him into it in the beginning, he’d clearly taken to evil like a duck to water.

Call put down the diary and went to the window, looking out at the afternoon sunlight dappling the grass. He was afraid he was going to throw up. He felt like a storm was in his head.

But after a few moments, he felt steadier. And then a few minutes after that, something new occurred to him. For years, Call had been afraid that he was too sarcastic, too mean-spirited, too willing to cut corners. He’d imagined a straight line from accruing too many Evil Overlord Points by not taking out the trash and eating the last slice of pizza to leading an army of the Chaos-ridden.

But Call knew he would never do what Constantine had done to Jericho — never steal pieces of the soul of someone he loved. He knew that he would never murder someone for no reason. If that was what evil was, he wasn’t going to wind up that way by accident.

Maybe he should stop worrying that he was becoming Constantine Madden and start worrying about Alex. Alex, who wanted power and wasn’t afraid to kill for it. Alex, who might be willing to do everything Constantine had done and more.

Tamara and Jasper were right: They had to get away from here and they had to do it quickly, before Alex got used to what his power could do, before Master Joseph stopped believing in Call and used the Alkahest on him.

But for all his evil, Constantine had been right about one thing. Death wasn’t fair. Aaron shouldn’t have died, and if Call could bring him back, bring him back to life, not as a Chaos-ridden, then one good thing would have come out of Constantine’s horrible experiments, his terrible war.

But to do it, he had to crack the code. Over the days they’d been here, Call had heard about and read about so many experiments Constantine had tried. What hadn’t he thought of?

There had to be something, some clue.

Call thought about the entry he’d read, the one where Jericho had seen himself mirrored in the woman’s face — as though she was being animated by a piece of his own soul.

There was something there, something that tugged at Call’s thoughts.

When Call was a baby, Constantine must have done something very much like that — pushing his whole soul into Callum Hunt’s body. Why had that worked?

Call frowned, concentrating.

And then, all of a sudden, he had an idea. A real idea, not one of those stumbling-in-the-dark, maybe-it-will-work ideas that he and Alex had been pursuing with their fruitless experiments.

Tucking the diary in the pocket of his flannel, Call made his way to the experiment room where Aaron was kept and did the one thing that he’d been avoiding — he went to the table where Aaron rested and pulled back the covering from his face.

“I hope you’ll forgive me,” Call said.

If he got it right, everything would be okay. They could all escape to the Magisterium and Call wouldn’t even be put in jail, since there was no way to lock up someone for the murder of a living person. They would return triumphant, with Master Joseph’s Chaos-ridden army. And if Tamara only wanted to be Call’s girlfriend because she was grief-stricken or something, like Jasper thought, well, maybe she would come to like him. Maybe he could convince her.

So long as Aaron was okay, he was sure she’d forgive him for how he got that way.

The room was full of shadows. Aaron lay still and waxy and white on the table, his face slack. He looked like Aaron and not like Aaron. Whatever it was that gave Aaron his personality and force was gone.

His soul, Call told himself. Name it what it is. He hadn’t believed in souls before he’d gone to the Magisterium, but Master Rufus had taught him how to see Aaron’s.

He placed his hands on Aaron’s chest. He’d touched him before, with Alex there, but now it felt strange. Like he was bidding Aaron good-bye.

But he wasn’t. The opposite, in fact. He forced his mind back from the dark paths it wanted to go down, the paths that reminded him that he was alone in the room with a dead body. Every horror movie he’d ever seen was competing to freak him out. This is Aaron, he reminded himself. The least scary person I know.

Constantine had used his brother’s soul, had torn off pieces of it to fuel his experiments. But what he hadn’t done was what Call was about to do. He hadn’t used a piece of his own soul.

Call kept his hands on Aaron’s chest, and reached down deep inside himself. He tried to remember what it had been like, seeing Aaron’s soul. He thought of what made him himself — his earliest memories: Alastair’s face, the streets of his town, pavement cracking under his feet. The gates of the Magisterium, the black stone in his wristband, the way Tamara looked at him. The feeling in his chest of Aaron’s magic pulling at him, what it was like to be a counterweight, the blackness of chaos …

Darkness in the form of smoke spread from his fingers. It spilled over Aaron’s chest like ink, wreathing his body.

Call gasped. Energy felt like it was pouring out of him, through his hands, making his body vibrate. He could feel his own soul, pressing against the inside of his rib cage.