“Okay.”

Nervous energy is building inside me as we come closer to confronting Paul. Or not—we might have got it wrong. This isn’t necessarily our dimension’s Paul Markov at all. What if he’s fled somewhere else entirely?

Then we’d have to jump into a whole new dimension, with a new set of rules, and maybe an even greater distance to cross to reach each other. The thought of it makes my head hurt.

And yet, a new dimension might be one where I’d be with my parents. Both of them. By now Mom feels almost as lost to me as Dad.

What is Mom doing right now, back home? Theo and I left a message explaining what we were doing; she would have lost it when she read that, but without a Firebird of her own, she can’t follow us. It’s awful to think of her being scared about me and Theo when she’s still so raw from losing Dad, but when we decided to go, I didn’t stop to think about how long we’d be missing in our own dimensions. We’ve been gone for a day and a half so far.

I wonder if they’ve had Dad’s memorial service—they couldn’t even have a real funeral, couldn’t even give him a true resting place—

No. I can’t let this get the better of me now. This close to our goal, I have to stay strong.

“Show me how to use the Firebird,” I say, pulling mine up from within my shirt.

“You’ve got the basics, right?”

“I don’t mean the basics.” This is difficult even to say. “I mean, show me how to use it to kill Paul. Our Paul.”

“You want to keep it down?” Theo glances around us; we’re surrounded by commuters. But they’re too absorbed in their own holoscreens and headphones to have heard a word I’ve said.

I insist. “Show me.”

“Listen. For your safety and my peace of mind, let’s leave that part to me, okay?”

“My safety isn’t one of our priorities here.”

“Speak for yourself,” he says, so intense that once again I find myself both thrilled and afraid of what it might mean.

My voice softens, but my resolve doesn’t. “You need to show me how to do it, just in case.” In my heart I know it’s my job to kill Paul—my duty, my right—but I also know that’s not an argument Theo wants to hear. If he’s worried about safety, fine, we’ll talk about safety. “If something happens to you, I have to be able to defend myself.”

Theo still looks wary. “You understand that this isn’t easy, right? Paul either has to be down for the count before you do this, or you have to have grabbed the Firebird from around his neck—assuming he’s got it on him. Which he might not.”

Paul might have his locked in a safe somewhere. But I’d bet anything he hasn’t. Theo and I are still wearing ours, because this thing is too precious, too valuable, to keep anywhere else but right next to the heart.

“I understand,” I say. “Show me.”

So Theo leans close and shows me a fairly elaborate set of twists and turns of the Firebird’s many layers and gears—by pantomime, of course. There are so many steps to the process that I can hardly even begin to memorize them all. “Why does this take so long? How is anybody supposed to do this in a crisis?”

“Nobody’s supposed to do it, period,” he answers. His head is so near mine that one of my curls is brushing his cheek, and he doesn’t push it away. “We were building ways to travel through dimensions, not killing machines. What I’m showing you is technically a reset—something you should only do in your home dimension, to allow the Firebird to . . . connect to a different person, a different dimensional resonance, you see what I’m saying?”

“Kind of.” I’m letting my frustration get the better of me. “I wish it were easier, that’s all.”

“It has to be difficult, because it’s fatal to anyone not in their home dimension. We didn’t want anybody doing this accidentally while they were traveling.”

As I watch Theo’s hands go through the sequence, over and over, I think of it again—the reality that I’m going to kill someone. An actual person, even if he’s not in his own body at the time.

He’s in someone else’s, I remind myself. You’ll be setting this world’s Paul free. But I can’t work up much righteous indignation while I’m shanghaiing someone else’s body myself.

And it’s not some anonymous stranger. It’s Paul. The one who looked like he’d never received a nicer birthday gift than the lopsided cake Mom baked for him. The one I once teased for buying all his clothes at thrift stores—and then felt so bad when I saw that he was embarrassed, because he didn’t shop there to be a hipster, he did it because he was poor. Paul, with his gray eyes and soft laugh and lost look, the one who held me against his chest when I was afraid . . .

Paul was able to look at all the good in my father, all the love Dad had given him, and go on to murder him without blinking an eye. Why can’t I do the same? Why can’t I be as hard as he is? I’m the one who has a reason, the one with a right to kill. I shouldn’t be the one who feels guilty and horrible and sick.

For Dad, I tell myself, but for the first time it rings hollow.

My stomach churns, and the monorail car feels too warm. I suck in a deep breath, attempting to steady myself, and Theo glances over. “You okay?”

“Yeah,” I say shortly. “I think I’ve got it.”