I would’ve known that even if Mom and Dad hadn’t already told me. “Wouldn’t you want your child back? But it’s impossible. Josie splintered into too many pieces. My parents know there’s no way they can ever re-create her again.”

“There’s one way,” Paul says. “One thing they can do to every dimension Josie ever visited, to make sure each splinter of her consciousness returns home.”

Theo and I glance at each other; he’s as bewildered as I am. This outstrips any of our research at home. I ask Paul, “What do they have to do to all those dimensions?”

Paul speaks gently, as if he could soften what he says next. “Destroy them.”

Twenty minutes later, I’m standing face-to-face with versions of my parents gone pale as ash.

Paul gave me the directions to find them. This apartment must be what counts as luxury in this dimension, but to me it looks bare and soulless: no houseplants, no chalkboard wall scribbled with equations, no piles of books. I could almost believe my parents had chosen to live in a hotel room instead of a family home—it’s that impersonal and cold.

“You tried to find your version of Theodore Beck, didn’t you?” Mom is doing that thing where she’s really mad but is trying to hold it back for a Reasonable Discussion. “Below is dangerous, sweetheart. You shouldn’t have—”

I don’t need to hear it. “I found Theo. And Paul.”

My parents exchange a glance. Dad says, “I suppose you’re not going to tell us where they are.”

“No, I’m not. You’re going to tell me what . . . what you’re going to do about Josie.”

I don’t repeat what Paul told me out loud because I still don’t believe it. I can’t.

My father looks like he doesn’t know what to say, or that he’s too ashamed to say it. Mom, however, has regained her poise. The only sign of her discomfort is the way she hugs herself, as if she were trying to keep back the nonexistent cold. “Journeys through the dimensions are dangerous, even for a perfect traveler. Of course we don’t have to tell you that; you’ve faced considerable dangers yourself. Surely, at some point, you’ve asked yourself whether these journeys shouldn’t be abandoned completely.”

I have, but the doubts have never been more than a whisper in the back of my mind. The amazing things I’ve been able to see—the different selves I’ve been, and gotten to know in other worlds—for me, that outweighs the scary parts. So far.

“After Josie’s death, we first thought we should abandon the project altogether,” Mom continues. “The risks were too high to justify mere curiosity, or even technological advancement. But then your father and I spoke with Wyatt Conley, and we realized we had a new goal. One worth any cost. Worth every sacrifice.”

“You want Josie back,” I say. “But what are you going to do to make that happen?”

I want them to contradict me, to repeat that re-creating Josie after her splintering is an impossibility. Or if it isn’t, to tell me the solution is something justifiable.

But from the way my parents go still, I know Paul told me the truth. Triad may be motivated by sincere love for my sister—but their plans are more horrible than anything my Wyatt Conley ever dreamed of.

My mother walks closer, standing directly in front of me. “Marguerite, the splinters of Josie’s soul are scattered too widely for us to collect. But if that dimension could no longer contain her—”

“Because it ceased to exist?” I ask.

After a moment, my dad nods. “Nothing less would work.”

I’m unnerved in a way that feels like physical disorientation, like the entire planet began spinning on a completely new axis. My whole life, I’ve joked about “Mom’s crazy theories,” though I always knew they weren’t crazy, just way out there. But what I see in my mother’s face now—and in my father’s, too—it’s insanity.

Not the metaphorical kind. Real, true madness has claimed them both.

“You can’t destroy an entire dimension.” I explain this slowly, like somehow that will help them understand. “Even if it weren’t completely evil—I mean, how? There’s no bomb big enough to take out a universe, much less several of them.”

“Marguerite, think.” Mom goes into professor mode, startlingly familiar in this bizarre moment. “Resonances between the dimensions are remarkably sensitive, as you should know. Remember, they can only be altered to create a perfect traveler once in each dimension.”

I’ve never understood the scientific explanation behind “resonances,” but the implications are clear. “Sensitive means—fragile. Breakable.”

Dad smiles, encouraging despite his strain, the way he acted when I kept having trouble learning to ride a bike. “And each universe strains to achieve perfect balance. All we have to do is return it to its fundamental symmetry.”

The memory of my walk in Muir Woods with Paul comes back so vividly I can smell the forest air. He stood in one small patch of light as he told me about the way that fundamental symmetry broke at the very dawn of creation. If it hadn’t—if matter and antimatter were equal, gravity and antigravity too—then the universe would destroy itself in an instant. We wouldn’t even know the disaster was happening—had happened—because time would collapse too.

“How do you do that? How is it even possible?” I whisper.

“The device is surprisingly simple,” my father says. “Bit of a surprise nobody thought of it before. Then again, if anyone did think of it, they had the sense not to build it.”

I grab at the only hope I see. “But you can’t bring a device to another universe! Only consciousness can travel between dimensions. Not matter.”

“Not most matter.” My mother points to the Firebird hanging around my neck. “We’ve been experimenting with various alloys and compounds. It won’t be long before we’re able to construct a device that can travel as easily as the Firebird. Though, of course, not just anyone can activate it. Most people would be erased in the universe’s collapse, without being able to escape.”

“Only a perfect traveler,” I say.

Finally it all makes sense. I knew Conley was too fixated on me, that there were too many other ways for him to get his dirty work done for him. What I didn’t know was just how dirty the work would be.

“Wait, wait, wait.” I form the time-out sign with my hands. “You mean, you want me to destroy entire universes?”

“Josie shattered into many pieces, too fragmentary to collect. But it wouldn’t be impossible to travel to each of those worlds. After all, you needn’t stay long.” Mom puts a hand on my shoulder, a touch meant to soothe that instead makes my skin crawl. “You won’t be killing anyone, Marguerite. The entire dimension will simply be erased from the multiverse. No one will feel any pain. No one will even know.”

When a dimension died, it would take its entire history with it. The people within it wouldn’t die; they would never have been born.

I think of the Warverse, of Josie as a fighter pilot. Or my parents as military researchers trying their hardest to keep their country’s hopes alive. Of Theo as the soldier who sneaked into my room at night and searched for moments of romance in that gray, scary time.