THE FIRST TIME I TRAVELED TO ANOTHER DIMENSION, I intended to take a life. Now I’m trying to save one.

But I can’t do that unless I save myself. At the moment, I’m running through the winding streets of a near-medieval Rome, trying not to get burned at the stake.

Welcome to the nonstop fun of traveling through alternate universes.

“She is the sorcerers’ daughter!” someone from the mob shouts. “She bears the tools of their witchcraft!” Her voice echoes off the cobblestones, just like the jeers from the crowd around her. A few of them hold burning torches, the better to chase me through the night.

My parents are scientists, not sorcerers. In this universe, looks like nobody knows the difference.

What I’m carrying in the pockets of my robe or cloak or whatever you’d call this shapeless red thing—it’s not witchcraft. It’s a spyglass, a.k.a. a primitive handheld telescope. This six-inch-long gadget looks like a prop for steampunk cosplay: tortoiseshell sides, brass fittings, lenses ground by hand. But this might just be the tool that brings this dimension out of the Dark Ages—assuming it doesn’t get my entire family killed first.

Panting, I dodge around every corner I come to, paying no attention to where I’m going. It’s not like I have any idea where I am anyway. When I leap into one of my other selves—the other Marguerites, who live in these parallel dimensions—I don’t get to access their memories. Some of their knowledge and ability carries over, but those are only the deeper, no-longer-wholly-conscious things. Knowing where the hell I am in this version of Rome? No such luck.

All I know is that I have to get away. Finding the Castel Sant’Angelo—and Paul, who should be there—well, that has to wait until I’m safe.

Of course, I could escape this dimension at any moment, thanks to the heavy weight on a chain around my neck. To anyone in this dimension, and virtually anyone in ours, it would look like nothing more than a large, fairly elaborate locket—if they even noticed it, which they probably wouldn’t.

This isn’t any old necklace. This doesn’t belong in their reality. This is the Firebird.

The Firebird—the one and only device that allows human consciousness to travel through alternate dimensions. The invention of my mother, Dr. Sophia Kovalenka, with the help of my father, Dr. Henry Caine. The thing that can instantly transport my mind out of this universe completely and send me back to my own body, my own home, and safety. Even as I run through an alternate Rome in an ankle-length woolen dress and cloak, my stiff boots sliding against the rain-wet cobblestones on the road, I keep the Firebird clutched in one hand; if I lose this thing, I’m screwed.

But I won’t go. I can’t leave this dimension until I do what I came here to do.

A couple more twists and turns through dark alleyways, and I finally manage to lose the mob. Although I can still hear murmuring and shouting in the distance, I have a moment to catch my breath. The frantic thumping of my heart begins to slow. My back is to a wall the color of terra-cotta; the only illumination comes from a few lanterns and candles visible through windows that have no glass. And, of course, the stars. I look upward, momentarily dazzled by how many more stars you can see in a sky unclouded by artificial light.

The view around me could have been taken from any one of a hundred early Italian paintings I’ve studied. This is a world without electricity, where only fire shows the way after dark. A cart pulled by a donkey rattles along in the distance, stacked high with bags of something, probably grain. Forget Wi-Fi, tablet computers, or airplanes—here, even steam engines are centuries away. It’s not that I’ve traveled back in time, though; the Firebirds don’t do that. But some dimensions develop faster, some slower. I’ve already been to futuristic worlds where everyone communicates by hologram and travels by hovership. It was only a matter of time before I reached one where the Renaissance is still in full swing.

Not that this is exactly the same as our Renaissance: The clothing looks more like tenth or eleventh century to me, and yet the telescope my parents have invented didn’t come into being in our world until long after that. Also, somehow, there doesn’t seem to be any old-fashioned gender roles in place, or any gender roles at all. The priest who condemned me to the mob was a woman. I’ll cheer for equality later.

The man I spoke to told me I could find Paolo Markov of Russia at the Castel Sant’Angelo. I imagine Paul chained in a castle dungeon, being beaten or even tortured, and I want to cry.

This is no time for tears. Paul needs me. Crying can happen later.

And once I’ve handled everything else, I’ll deal with Wyatt Conley.

The angry buzz of the crowd has faded. Where do I go now? I’m surrounded by dark, twisting alleys and a jumble of buildings filled with people I can’t trust. They said the Castel Sant’Angelo was to the west, but which way is west? Without the sun in the sky for me to judge by, I can’t guess what direction to go in. Still, I have to begin somewhere. One more deep breath, and I start toward a narrow street that leads down a seemingly quiet road—

—then gasp as a hand closes over my shoulder.

“Not that way,” a woman whispers. A noblewoman, I realize, her face all but hidden under her blue velvet cloak. “They may gather near the Pantheon.”

I don’t know what that is, but if the mob is going to be there, I’ll head in another direction. “Thanks.”

“Your parents are leading us to wisdom,” the noblewoman says gently. “The others fear what they do not understand.”

She steps forward, just enough for some of the dim lighting to illuminate her face—thick golden hair, strong square jaw—and it’s all I can do not to gape at her.

Her name is Romola. If I ever knew her last name, I’ve forgotten it. I encountered her in the very first alternate universe I ever visited: a futuristic London where she was the daughter of a duchess. Spoiled, rich, high on drugs, and drunk on champagne—Romola dragged me from nightclub to nightclub while I drank as much as she did. I was exhausted, afraid, and heartsick; it was only two days after the police told my family that my father had died. Dad turned out to be fine—well, if “fine” includes “kidnapped into an alternate dimension.” But I didn’t know that at the time. So those surreal, sick, miserable hours with Romola loom larger in my mind than they should. It seems like I knew her forever, not just for one weird day.

I shouldn’t be surprised to see her again. We’ve learned that people usually cross paths in many dimensions—that no matter how different the worlds may be, fate draws us together.

“Are you well?” Romola puts one hand to my forehead, like my mom did when I was little. “You seem dazed. No one could blame you, after what they’ve put you through.”

“I’m fine. Really.” I pull myself together for the rest of my escape. “I need to get to the Castel Sant’Angelo. Which way should I go?”