“Thanks,” I say, but then I can’t think what to add.

Fortunately Romola’s ahead of me. “You can make it up to me by getting the popcorn. And M&M’s! They’re so good mixed together.”

Her presence here weirds me out in a way I can’t explain, even to myself. She’s someone I’ve met before, but never known well. I thought of Romola as—an accident, a coincidence. Not a person who was supposed to mean a lot to me.

Just like Paul should be everyplace, everywhere with me, and he’s not.

The movie turns out to be one I’d meant to see at home, and Romola’s right about the popcorn-plus-M&M’s mix. So by the time we’re walking out of the theater in the late afternoon, my mood has improved. This world is no more dangerous than my own; Mom, Dad, and Josie are all alive and well; and there’s a text message waiting for me from Theo, which says only, Turns out I live in Alphabet City. Headed your way.

“Tonight’s the big dinner, isn’t it?” Romola’s smile turns almost wicked as she says it. “You have to tell me everything.”

As casually as possible, I ask, “What do you want for the highlight reel?”

“Let’s see. The absolute most awkward question your parents ask him. And oh, if he looks intimidated or even unsure at any moment, get a photo if you can, would you? I can’t wait to see my big, bad boss being interrogated by your parents.” She’s joking, but not; her glee at the thought of this dinner is real.

So in this world, we met through her boss? Maybe she works for some other world-class scientist; that might explain how Romola and I keep coming together. Right now she’s looking at me for a reply, one I’m not sure how to make, so I bunt. “Oh, sure, I’ll film the whole thing, zoom in on his face. He won’t notice that.”

The sarcasm covers my ignorance well enough. Romola just laughs. “All right, all right, we’ll talk next week, and you can tell me all about it.”

“Okay.”

Romola hugs me before she leaves. Somehow I manage to return the hug without stiffening up. Then I walk to the closest subway station and spend a while searching on my smartphone until I find an app that will tell me how to get to any address via public transit.

For the record: the New York subway is even more disgusting than Bay Area Rapid Transit. I didn’t think that was possible. It’s faster, though, because within ten minutes I’m staring up at the high-rise apartment building where I apparently live. A uniformed man at the door smiles at me. “Miss Caine. Welcome back. How was your day?”

That must be the doorman. “Great, thanks,” I manage to say before ducking inside; it doesn’t look like any more conversation is required.

Apartment 28G ought to be on the twenty-eighth floor, so I head up in the elevator. As I walk toward the apartment door, I hear the faint strains of “Here Comes the Sun” in the hallway, and I grin. Dad’s home.

I walk into an apartment that’s even smaller than the house we had in the poverty-stricken war dimension—but unlike that place, this is immediately recognizable as our home. A houseplant hangs from a hook in one corner, with its long vines trailing along the tops of the windowsills. Piles of books and papers sit on the table and in the corners. The walls are painted a sunshiny yellow, and on the leather sofa sits my father, laptop on his knees, typing away.

“There you are,” Mom says, as Dad glances my way just long enough to smile. She walks out of what must be her bedroom wearing a dark blue sheath dress—simple enough, but pretty fancy for someone who normally sticks to jeans and threadbare sweaters. Head tilted, she puts on an earring as she says, “I didn’t think you’d make it back before dinner.”

“Here I am. Hey, you look nice.”

Mom sighs. “I don’t want Josie to think we’re not taking this seriously.”

“I only wish I could believe she wasn’t taking this seriously,” Dad says without looking up from his computer. “Honestly. After only two months?”

“Now, Henry. We made up our minds after less than a day.” My mother rests one hand on my father’s shoulder, and he closes his laptop to smile at her. She continues, “The speed of their courtship isn’t the issue. Or it wouldn’t be, if I had a stronger sense of who he is. But—there’s something elusive about him. Something hidden. I don’t like it.”

“Tonight’s our chance to question him,” Dad says. “Don’t think I don’t intend to make use of it, no matter how la-di-da this restaurant is.”

“You sound like a police investigator going after a suspect.” Mom leans down and kisses his forehead. “Good.”

The dots aren’t difficult to connect. Josie’s dating someone seriously—Romola’s boss, from the sound of it. This isn’t as remarkable to me as the fact that Josie’s either engaged to him or about to be. Normally my sister seems to go for quantity over quality with her boyfriends; she’s not a party animal or anything, but lots of guys love the same adrenaline sports she does, so she meets someone new all the time. Josie always swore she’d only get serious about a guy after she had some idea where she’d end up, professionally speaking. I don’t want to sacrifice my dreams for anybody, she said once. And I don’t want him to have to sacrifice his dreams for me. That’s kind of hard core—but that’s Josie.

Here, however, some guy won her over in just two months? This man I have to see.

“How long until we leave?” I ask.

Dad says, “Thirty minutes or so. I ought to grade a few more midterms, shouldn’t I? Say no.”

“Yes,” Mom calls from her room. Dad sighs.

I find my room on the first try—and exhale in relief as I see my paintings on the walls. My style here is much the same as at home: very realistic, except for my use of color. Here, I stick to a muted, limited palette for each portrait, giving the finished work a definite mood. Josie’s picture glows with reds and pinks; Mom’s reflects cerebral silvers and blues; Dad’s has soft sunny golds; and . . . then there’s Theo.

For his portrait I used bronze, orange, burnt sienna—colors both grounded and yet somehow electric. His dark eyes seem to shine as he looks out from his picture.

I don’t see a portrait of Paul.

Frustrated, I run a search on my tablet. “Paul Markov, physicist” comes up with zero results. So does “Paul Markov, scientist.”

My fear comes rushing back. Wouldn’t Paul be a scientist in any world he possibly could? In a dimension so much like our own, wouldn’t he go into physics, just like before? It seems as if nothing could keep him from that destiny, unless he’s seriously ill, or his parents never emigrated from Russia.

How am I supposed to find him if he’s in Russia? Over there, his name is so common he might as well be called John Smith. Besides, how would I even get there?

I try again, with his name and his birthday. Then an image shows up—something from a school webpage, some years old now—but I smile as I see it. That kid in a plaid shirt, surely no more than ten years old: I’d know him anywhere. Paul doesn’t keep any photos from his childhood, so I’ve never seen him as a little boy before. Of course he was completely adorable. My fingers trace over the screen, outlining his baby face.