Paul is gone. He’s leaped ahead, into yet another dimension.

Which means the guy standing in front of me now is . . . still Paul Markov, but the Paul who belongs in this world.

The train pulls into its next stop. I grab one of the poles to steady myself; Paul does the same, but clumsily, like he hardly understands what’s happening. Then I realize he doesn’t. He’s standing here on this train without any memory of how we got here, or even who I am.

“What’s going on?” says Paul/not Paul.

“I—” How am I supposed to explain this? “Let’s get off the train, all right?”

Although Paul looks understandably wary, he follows me out, through the station, and onto the street.

We’re in an entirely different section of London now, or so it seems; this part looks more like the city I remember, with more old buildings, no hoverships in the sky. It’s started to rain again. We duck under a storefront awning, and by now Paul looks less confused, more unnerved. “Where am I?”

“London.”

“Yes, of course,” he says, and the way his eyes narrow when he’s unsure and irritated is so familiar that it’s difficult for me to believe this isn’t my Paul. “I came in this morning for the tech conference. To hear Wyatt Conley. I’d been planning it for weeks—but I could swear I remember getting off the train. Then it all goes . . . blank.”

He was coming to the tech conference anyway. Of course he was. Why wouldn’t a physicist be interested in one of the innovators of the age? “Do you not remember anything of the past, I don’t know—two days?”

“I remember . . . some things,” Paul says. His expressions, the way he moves—it’s all slightly different from our Paul, the one I know, the one who just ran away from here. How strange it is to be able to tell the difference in how he tilts his head. “But who are you? Who punched me?”

I did that. Theo and I did that to you, and you’re a stranger who never hurt either of us. “There was a fight. It’s over. Nothing bad happened.”

“But—” He stares down at his broad hands, realizing his knuckles are bruised. His lost expression is suddenly so like Paul’s that it makes me suck in a sharp breath.

I find myself wishing I could explain.

So I say, as gently as I can manage, “You wouldn’t believe me if I told you. Just—go home. It’s all right. You won’t see me again.”

Although he clearly wants more answers, Paul must want to get the hell away from the crazy stranger even more. He backs away, out from under the awning, until raindrops patter against his long coat and his disheveled hair. Then he turns and walks into the London crowd, lost again in an instant.

Only then do I realize my ring has been vibrating for a while now. I hit it, hoping to get Theo. When his face appears before me in three-dimensional light, I’m hopeful—but then I realize it’s a message.

“Marguerite, I hope to God you’re okay.” His face is stark—afraid for me. Theo continues, “Paul jumped out of this dimension a few seconds ago. I’m guessing you already know that. We have to go after him. Don’t worry—I set your Firebird to follow him wherever he leaps, exactly like mine. I feel . . . beyond strange, going on ahead of you, but I know you’d tell me not to let Paul get away, no matter what. Justice for Henry, that’s what matters most.”

I nod, as though his message could see me. But it’s only a hologram talking into the void.

Theo smiles, tense and nervous. “We’ll meet in the universe next door, all right, Meg?”

“Yeah,” I whisper. “Next door.”

Although I take my Firebird in hand, I don’t set it for the next jump right away. First I look out at the grimier London in front of me, the one with technological marvels pinned to or floating in front of every person, and each one of them too distracted and careworn to notice. I try to imagine how this Marguerite will feel when she comes to alone in a few seconds, wondering why her heart is pounding.

It seems that she won’t remember much. But—I don’t need the reminders the way Theo does, the way Paul appeared to. The experience of traveling is different for me than it is for them. So maybe this Marguerite’s experience will be different too. Possibly she’ll retain some fragment of this, an image or a sensation that belonged to me and now is shared between us both.

So I flood my mind with thoughts of my parents, the ones she lost so long ago. I think of them laughing while I painted the rainbow table. Of Mom holding me on her shoulders at the natural history museum so that I could look right up into the skull of a triceratops. Of Dad taking me around town on his bike when I was still little enough for the kiddie seat—one of my earliest memories—him laughing with me as we swooped downhill together.

I hope this Marguerite can remember them a little. That it will make some dent in the terrible grief that has walled her into this life . . . and maybe give her enough hope to break free.

Then I begin manipulating my Firebird, turn the final gear, and think, Oh, God, what’s next? What’s next?

I collide with myself—my other self—and this time I lose my balance entirely. In the split second I’m wobbling in midair, I realize I am descending a staircase. Apparently this is a very, very bad moment to have a cross-dimensional traveler hop into your body, because then you miss a step and—

I manage to get my hands in front of me as I fall, which doesn’t keep me from landing on the stairs hard, but at least lets me brace my roll down the next several steps until I catch myself. A necklace around my neck breaks, and I hear beads rolling in a dozen directions. All around me, people cry out and hurry to my side. Dazed, I lift my head.