Even as I walk along the street by the South Bank of the Thames, I can tell computers were invented a little earlier here, because they’ve advanced further. Several people, despite the drizzling rain, have paused to bring up little glowing squares of light—like computer screens, except they’ve appeared in thin air in front of their users. One woman is talking to a face; that must be a holographic phone call. As I stand there, one of my wide bangle bracelets is shimmering with light. I lift my wrist closer to my face and read the words, written on the inside in small metallic type:

ConTech Personal Security

DEFENDER Model 2.8

Powered by Verizon

I’m not quite sure what that means, but I don’t think this bracelet is just a bracelet.

What other kinds of advanced technology do they have here? To everybody else in this dimension, all this stuff is beyond routine. Both the hoverships above London and the no-rail monorail snaking along overhead are filled with bored passengers, for whom this is just the end of another dull day.

There’s no place like home, I think, but the feeble joke falls flat even inside my own head. I look down again at the high heels I wear, so unlike my usual ballet flats. Ruby slippers they’re not.

Then I remind myself that I’ve got the most powerful technology of all—the Firebird—hanging around my neck. I open the locket and look at the device inside.

It’s complicated. Very complicated. The thing reminds me of our universal remote, which has so many keys and buttons and functions that nobody in my household—which contains multiple physicists, including my mother who is supposed to be the next Einstein—none of us can figure out how to switch from the Playstation to the DVR. But just like with the universal remote, I’ve learned a few functions, the ones that matter most: How to jump into a new dimension. How to jump back from one if I land somewhere immediately dangerous. How to spark a “reminder,” if needed.

(The idea was that people who traveled between dimensions wouldn’t remain fully conscious throughout—that they’d be more or less asleep within the other versions of themselves. So you can use the Firebird to create a reminder, which would leave your consciousness in control for a while longer. Well, so much for theory. As far as I can tell, the reminders aren’t necessary at all.)

As I look down at the glittering Firebird in my palm, I remind myself that if I learned how to work this thing, I can handle anything this dimension has to throw at me. Re-energized, I start observing the people around me more closely. Watch and learn.

A woman touches a metal tab clipped to her sleeve, and a holographic computer screen appears in front of her. Quickly I run my hands over my own clothes; this silver jacket doesn’t have anything like that on the sleeves, but something similar is pinned to my lapel. I tap it—and jump as a hologram screen appears in front of me. The hologram jumps with me, tethered to the metal tab.

Okay, that’s . . . pretty cool. Now what? Voice commands, like Siri on my phone? Can something be “touch-screen” if there’s no screen to touch? Experimentally I hold out one hand, and a holographic keyboard appears in front of the screen. So if I pretend to type on it . . .

Sure enough, the words I type appear on the screen, in the search window: PAUL MARKOV.

As soon as the eighty zillion results pop up, I feel like a fool. Markov is a fairly common last name in Russia, where Paul’s parents emigrated from when he was four; Paul, which has a Russian form too (Pavel), is also popular. So thousands and thousands of people have that name.

So I try again, searching for Paul Markov plus physicist. There’s no guarantee Paul would be a physics student here, too, except that I have to start somewhere, and apparently physics is the only human endeavor he remotely understands.

These results look more promising. Most of them focus on the University of Cambridge, so I pull up the one titled “Faculty Profile.” It’s for a professor with another name altogether, but the profile lists his research assistants, and sure enough, there’s Paul Markov’s photo. It’s him.

Cambridge. That’s in England too. I could get there within a couple of hours—

Which means he could get here within a couple of hours.

We can track Paul, because the Firebirds allow us to know when a dimensional breach occurs. But that means Paul can also track us.

If this is the right dimension—if this is where Paul fled after cutting my dad’s brakes and stealing the final Firebird—then Paul already knows I’m here.

Maybe he’ll run away, fleeing to the next dimension.

Or maybe he’s already coming after me.

3

I HUG MYSELF AS I WALK THROUGH THE MIST. IT FEELS AS though I’m splintering into a dozen directions at once—grief, then rage, then panic. The last thing I need right now is to lose it. Instead I force my mind to go to the place that always calms and centers me: painting.

If I were going to paint the dimension I see in front of me, I’d load my palette up with burnt umber, opaque black, a spectrum of grays—nothing brighter than that. I’d have to grind something into the paint with my thumb, some sort of grit or ash, because the grime here goes deeper than surfaces. Even the air feels dirty against my skin. There’s less old stone in this London than I remember, more hard metal. Fewer trees and plants, too. The chill in the air is sharp; this is early December, and yet I’m wearing only a short black dress and a flimsy jacket brighter than tinfoil.

(Yes, it’s definitely December. The devices allow dimensional travel, not time travel. “That’s another Nobel Prize altogether,” Mom once said cheerfully, like she might turn to it whenever she got a spare moment.)