There was no time—or oxygen—to ask what they’d been doing in the woods; we just ran.

At the top of the hill, we burst from the woods onto the moon-blanched gravel that lined the train tracks.

Loose rock slid out from under our feet as we threw ourselves up the bank. I lost my footing and fell onto all fours, pitching myself back up on the rails themselves. At the bottom of the bank on the far side of the tracks, Sofía and Levi were disappearing into the trees, but Art, Nick, and I wouldn’t have time to get down there before the man and his gun caught up.

His shouts were still ricocheting off the trees behind us.

I glanced up the tracks, searching for a better escape route, but the rails stretched out unobstructed for at least two miles. I spun the other way, deeper into Wayne’s property.

A couple of yards ahead, the tracks divided, each disappearing into a stone tunnel eaten up by moss and ivy.

“Come on,” I whispered, running for the mouth of the nearest one. It was overgrown, foliage hanging low across the entrance so we had to duck to keep from tangling in it as we slipped inside.

The stone walls shut out the moonlight and the shouts, even some of the heat, and when I turned away from the entrance, I could barely see anything.

Nick and Arthur followed, Arthur’s Vans shuffling over the worn-soft wood of the tracks and Nick’s high-tops faintly scraping along behind them. The overgrowth of grass sprouting up through the tunnel deadened the sounds of our movements, but behind us, the crackle of new steps on loose rock sent a shock of adrenaline through me.

I flattened myself to the tunnel wall, holding my breath. Nick and Arthur pressed in close too, like knotting ourselves together would be some kind of defense against a shotgun pellet.

Out in the shadowy blue beyond the tunnel’s mouth, the behemoth silhouette stepped onto the tracks and made a slow, counterclockwise turn, scanning for any sign of us.

I willed my heart to stop beating before its deafening pumping could give us away.

Go back, I willed him. You’re not going to shoot us for walking on your grass.

“Real tired of this,” the man let out. He had the voice of a smoker verging on sword-swallower, a scraped-raw tone.

My stomach flipped. My blood felt like it was bubbling, boiling, and my limbs were taut and trembly.

The man stepped closer and my pulse spiked.

He stopped suddenly and looked down at the tracks under his feet.

Beside me, Arthur gasped; Nick approximated a swear.

It wasn’t just me shaking. Tremors were racing through the tracks, shivering under our feet.

Outside, the man staggered back, studying the rattling rails.

My spine tingled as the trembling grew and grew, as if any second the world was going to break apart under us.

I lurched against the wall at the sudden shriek of metal. Out on the tracks, the man jumped back from the rails and gaped at them.

The shriek and snap sounded again, and this time, I caught a moonlit glimpse of the switch where the tracks merged.

Two more metallic shrieks came in quick succession as the switch flipped back and forth.

Train warning bells began to blare. Arthur’s arms flung out, pressing Nick and me flat to the wall, but he jerked back, releasing me, as a visible spark of light leapt from my skin to his.

He might’ve said something; I couldn’t hear.

The spastic screech of the rusty train switch screamed on one side of us, and the crossing bells raged from the other.

Outside, the man turned an anxious circle, then hurried off, running for the cover of the woods with his head ducked.

As soon as the man was out of sight, Nick bolted from the tunnel, but I didn’t move.

There was no train coming.

This time, I knew. This time, I felt it: I was doing this.

Me or the thing inside of me.

Art hadn’t moved either.

He stared at me through the dark. “Back at the house,” he whispered. “Those lights . . .”

I was watching the understanding dawn across his face.

“Arthur . . .” I began, gut twisting.

What could I say?

It’s going to be okay?

I’m going to figure it out?

I’m exchanging e-mails with an Internet stranger who says he can help me?

So whatever you do, just don’t waste your energy worrying about me?

“I knew it,” Arthur whispered.

“You . . . you knew?”

All at once, the life went out of the rails. The buzzing under my skin ceased, like a switch had been flipped. He already knew, and now I didn’t have to say it aloud. Didn’t have to acknowledge that something was inside of me, filling me with unstable energy and thoughts that weren’t mine and—

“I knew our alien must’ve given us something!” Arthur cried. “I knew something must have happened to us that night. I wonder—I wonder what else we can do.” A slow, glow-in-the-dark smile spread across his mouth. “Franny—Franny, this is amazing! How did we do it? We have to try it again.”

Everything inside me collapsed, condensed into something tiny and impossibly heavy.

He didn’t understand.

He thought this was the superhero origin story he’d been waiting for. He thought everything was going to be okay, better than okay.

I was a black hole, the force ripping all of them into a place where light and sound couldn’t reach them.