My heart thumps, and I feel like I might throw up. I bend over, my hands on my knees, trying to catch my breath.

My powers have been more and more erratic since Sofía disappeared, but they've never brought me back here, to this moment. And I've tried. I've tried to get back so many times.

I gather myself, breathing in the crisp morning air. I may not have meant to snap back to this time, but that doesn't mean I can't use it.

On the day Sofía disappeared, I had gone for a walk by myself. I went north to the gate on the boardwalk and then turned around and was heading back to the school. But I veered closer to the beach and went past the old camp ruins. They're state-owned property, and we're not supposed to hang out there. But that day I ignored the Doctor's rules.

I look around and then up. You'd be surprised how adept you get at using the sun to tell time when you never know when and where you're going to end up. Judging from the position of the sun, I figure that the past me, the me on a walk about to meet Sofía and screw up her life, is probably near the polio camp ruins.

The abandoned camp is left over from the days before vaccinations, when the sick had to be quarantined. It was built in the '50s for people with polio, but it remained open through the '80s. Now, after years of neglect, it's just a bunch of rotted wooden buildings that look like a haunted summer camp. Berkshire was built when the camp closed, and no one bothers to maintain the abandoned buildings.

I still don't know why I went there that day . . . but I did.

And that's where I saw Sofía.

To be accurate, I saw her shoes first. Bright red, perched on the edge of the remains of a shallow swimming pool at the center of a circle of broken-down buildings. It's nothing but a concrete depression now, no water or anything, and Ryan keeps talking about how it should be turned into a skate ramp, but Dr. Franklin says that's disrespectful.

She was just sitting there, her legs dangling over the edge.

"Hey," I said.

Sofía didn't respond.

I walked over and sat down next to her, her red shoes between us. It seemed strange that she'd taken her shoes off. The morning was cold, the dew on the blades of grass frozen like crystals. It was no longer quite winter but close enough. I guess Sofía was in denial about the weather.

"What's up?" I asked.

Still, nothing.

And that's when I noticed she was crying.

Not, like, loud, sniffling crying that makes your shoulders hunch and your face hurt. Just quiet tears leaking from her eyes, trailing down her cheeks, and dripping from her chin. She was so lost in her sadness that I wasn't even sure she was aware of my presence until I touched her cold face, wiping away one of the tears with the pad of my thumb.

"Hey," I said as gently as I could. "What's wrong?" I moved her shoes so I could scoot closer, but she stood up abruptly, stepping back from the edge of the pool.

"Nothing," she said, and I knew it wasn't true, but she started walking away, barefoot on the cold, sandy soil. I figured if it meant that much to her not to talk about it, then she could keep her secrets.

Still, I followed her. I knew she wanted to be alone, but there was something about the way she walked, something about the little hiccup sound she made as she wiped away her tears and pretended like they never existed . . . it didn't feel right to abandon her.

Maybe I should have left her alone. Maybe then she wouldn't have gone away.

As she passed by one of the old camp buildings, she whirled around. "You can go back in time, right?"

"Yeah," I said. I watched her closely. She wasn't acting like herself, but I didn't know how to make it better.

"Can you take other people back?"

I nodded. "Do you want to go back here?" I asked, waving my hand toward the abandoned buildings of the polio camp. "It's just a bunch of sick kids."

She shook her head. "No, not here. But, you know, I think maybe . . . maybe this place wouldn't be so bad."

"Sick. Kids. Just, like, buckets of sick kids all around being sick. Not my idea of a fun place."

"You don't understand," Sofía said. "When you're sick with, like, a terminal illness, something you live with forever, there are very few moments you can forget about it. It's like a lead weight inside your chest, cracking your ribs. Every time you move, you can feel that weight shifting inside of you. But then there are moments when, for whatever reason, the weight goes away. You forget you're sick. I bet this camp was full of those moments. That's what I'd want to see. That's what I want to feel."

She was right. I didn't understand.

"So where do you want to go?" I asked, still unsure of this wild mood of hers.

Sofía looked off into the distance, toward the ocean and the sun and forever, but she couldn't see any of that. "I want to go somewhere far away."

She didn't bother explaining any further. She just kept walking. I don't think she was going anywhere in particular, but we headed toward the state park. I thought about running back to get her abandoned red shoes so she wouldn't have to walk on the splintery wood of the boardwalk, but she veered left, where the ground was soft.

I look around me now. Any minute, past-me and past-Sofía will come around the bend and be standing right in front of me, at the chimney. It's where Sofía took me that day, right before she whirled around, her eyes blazing, her long, dark hair whipping back, and said: "Here."

"Here?"

"Can you take me back to this place? Back when there was just one family on the island, the ones who built this house?"

"It wasn't built here," I said. "It was built in Salem."

"Fine, then when the house was moved here. To . . ." She turned around, her eyes scanning the plaque. "Let's go back to 1692."

"I . . . um . . ."

"You can do it, right?"

"Yeah," I said immediately, wanting to impress her, to erase the doubt in her voice. "I've been back further than that. It's just . . . why?"

"I want to go away. I want to be as far away from this world as possible. Take me back further than 1692, I don't care. Let's go to the days when Native Americans were here. Lets go further. Let's go to the dinosaurs."

All my muscles were tense, and I moved very carefully, like I would if there were a wild animal in front of me. "I've never been that far back before," I said. I regretted telling her that I could take her back. I wanted to wrap her up in my arms and hold her tight, not fling her through time and space. I didn't realize it then, but a part of me sensed that she was running away, and I didn't want to let her go, even if I was going with her.

"I don't care, I just—" Her voice cracked. "I need to escape."

I took a deep breath and grabbed both her hands in mine. I didn't know what was wrong with her, but I knew I would do anything to make her happy. As I was holding her, I called up the timestream. I saw it expanding out from the two of us, strings erupting in every direction, each one linked to a different time and place. She couldn't feel it; she didn't react at all as I focused on the date on that chimney, on the house that once contained it, on the island of the past.

And then we were there.

We had been standing among ruins; we were now standing in front of a chimney with bright red bricks streaked with soot. A roaring fire blazed at the bottom, casting Sofía in an orange-yellow glow and flickering shadows across the wood floor. There were herbs drying in one corner, an iron cauldron bubbling in another. The house smelled . . . warm. It wrapped around us, peaceful and beautiful.

Sofía sighed. In that moment, I think, she was happy.

Then the door behind me flung open, and I could hear a man's deep, accented voice: "Oh my God."

I started to turn.

Sofía's hands slipped from mine.

And suddenly, like a rubber band breaking, I was snapped back to the present. I gasped for air, my entire body in shock, having been thrown through more than three centuries. My arms and legs trembled, and I fell to the cold ground, my fingers clutching the sharp blades of the long sea grass.

"What happened?" I said.

But there was no answer. Just the ruins of an ancient chimney.

Since then, I've spent every waking moment trying to find a way back to Sofía. But my powers have worked sporadically at best, and never in a way that would be helpful. Now, though . . . now that I'm here, back to the time before she was trapped . . . I have a chance.

I could save Sofía. I could stop my past self from taking her back, from leaving her stuck in a world that wasn't hers. I've tried so many times to reach this time and place again, and now that I'm here, I can fix it. I can make sure she never ends up in the past, abandoned, trapped where I can't reach her.

I hear voices down the path. It's past-me and Sofía. This is my chance. I can save her.

I stand up straighter, prepared to run to her.

I take one step forward, my voice already rising in my throat, ready to shout a warning . . .

I'm snapped back to the present.

I feel a cool hand on the back of my neck. "Hey," Gwen says softly. "You okay? You were gone there for a moment."

I nod, swallowing. I don't know why I expected this time to be different.

I can't save Sofía. I took her to the past, and I left her there, and I can't bring her back. I've tried and I've tried. Every time I get close to her, time snaps me away again.

She's trapped. And I put her there.