I feel my cheeks flush with heat. “That’s—it’s—why would Conley care about that?”

The angles of Paul’s face are carved more deeply by the flickering lights of code around us—his strong jawline, the searching quality of his gaze. “By now you’ve traveled to three parallel dimensions. What have you noticed about traveling? About your reaction to it—yours, specifically?”

“I remember things better than you guys,” I say. “I haven’t needed a single reminder.”

“Exactly. Theo and I need the reminders to know who we are. You don’t. In every dimension you can enter, you remain in total control throughout. Do you realize how valuable that is?”

I remember what Mom and Dad were talking about last night, and all their amorphous fears suddenly take shape, forming a wall around me.

Paul tilts his head, as if he’s studying me. “In this dimension, I learned—or this Paul learned—that Conley’s already sending spies into other dimensions. They’ve found ways to stabilize their spies for longer periods of time than the reminder shocks, for a day or two at a time, but their methods are still imperfect. Anyone who travels to another dimension remains vulnerable. Anyone except you.”

“There must be others,” I protest. “If I can do this, other people can too.”

“No. In our dimension, it’s only you.”

“You can’t know that! Think about it, will you?” Maybe Paul is paranoid after all. I brace my hands against the bed, trying to control my frustration as I ask, “What are the odds that the one and only person in our dimension who can travel like that would just happen to be the daughter of the people who invented the technology?”

Paul shakes his head. “It’s not random. It’s deliberate. Conley did this to you.”

“Did this?”

“The Accident. That day with the ‘overload test.’ You remember, don’t you?”

It comes back to me, more vivid than it was even when it was happening. That weird device Triad gave us, the way both Paul and Theo freaked out about it, the sense that I’d been in serious danger . . . the way Paul held me in his arms as though he’d nearly lost me . . .

He must see the realization in my face, because he nods. “You can only create a disruption like that once in a dimension. You can only use it to alter one person. Conley set it up so that the device would alter you.”

“Josie was there too.”

“She would have been the backup. Conley’s alternate target, someone else he could use to manipulate your parents. But I think he wanted you all along.”

“Why me?” But I haven’t forgotten what Paul said earlier, about being the only person all of them love. “He wants to use me against you. Doesn’t he?”

Paul nods.

Fate and mathematics. I can reach so many different versions of my parents—the people who discover inter-dimensional travel, the ones Conley will have to control in universe after universe if he wants to keep the technology for himself. Even though I want to think Conley could never force me to do his bidding, I know he could. All he’d have to do is threaten someone I love.

I ask, “Which Conley is doing this? The one from this dimension, or ours?”

“I think this Conley has been visiting our dimension for a while now. Months, probably. I’d say he was using our version, except I wonder if they aren’t actually working together.” Paul’s smile is thin and mirthless. “A conspiracy of one.”

Mom and Dad told me the spying might have already begun in this dimension, but I never realized Triad was spying on us. I shudder, and Paul looks pained, as though he hates himself for scaring me. He tried so hard to keep this secret, so I wouldn’t be scared.

And finally, finally, I understand.

“That’s why you ruined the data,” I whisper. “Why you stole the Firebird. You knew the faster we had the technology, the faster Conley would come after me.”

Paul nods. “When I realized what had been done to you, I knew they would test you soon. I thought—if I took our only good Firebird, and I made it difficult to build another—then that would put the test off for months. That was time I could use to try to reach this dimension and find out more about their plans, maybe learn something we could use.”

“Then why did we go to the other dimensions at all?”

He looks almost defeated, his broad shoulders slumping as he leans forward. His head is near my knee. “They were . . . wrong turns. Dimensions mathematically similar to this one. The universes next door. At first I thought London might be the right place, and I went to confront Conley there, but then you showed up and he didn’t recognize you. As for Russia, I would’ve left immediately if Azarenko hadn’t taken my Firebird.”

“Then you got here, and this is the world you’ve been looking for.”

Paul looks so tired. “I thought I’d have a chance to sabotage them from within. But this Paul had realized what was going on, and had already gone after Triad on his own. I guess he—he wanted to protect every version of you. Everywhere.”

Which is what Paul was trying to do when all this began: he was trying to keep them from finding out that they’d turned me into their perfect spy. Instead, I went chasing after him, because I was angry and ignorant and overwhelmed, and wound up proving the very thing he was trying to hide. “I messed it all up when I came after you, didn’t I?”