I slam my hand over my mouth, choking back my own screams.

"Don't look," America whispers. He turns his headlamp away from the chamber, and the entire space goes dark.

Tears run from the corners of my eyes, stinging the tiny cuts that cover my face from when my helmet shattered. I collapse to my knees, my hands shaking as I clench them into fists. My fingers are still tingling from when I let her go. If I could have just held on a little tighter . . .

"We can't stay here, Shawn." America tugs my arm firmly. "We've got to get moving."

I squeeze my eyes shut for a second, shaking myself from the freeze that's come over me. Elias is gone. Star is gone. My friends . . . There is nothing we can do for them now.

"Let's go," I finally respond.

I lead the way, with America right behind me. His headlamp reveals the rough, jagged path the tunnel takes. I brace myself between the rocks on my hands and knees as we go. The surfaces of them are slick with mold, like algae on the rocks of a jetty.

As I scoot between two steep rocks, my foot slips, and I fall a foot and a half before my ankle lodges between two stones.

"Shit," I hiss. Pain prickles up my leg as I try to yank my foot out. The jagged rocks grind and scrape against my skin through the fabric of my spacesuit. "Fuck!" Panic courses through me. It feels like my blood is turning to ice in my veins.

If I can't get my foot out . . . I'll be trapped here. I'll die in this tunnel, a slow, gradual death in the dark with nothing to keep me company but my own thoughts. I hyperventilate as I tug at my foot harder.

"Shawn." America touches me on the shoulder.

"I'm stuck!" I gasp. My eyes sting with tears.

America's light flashes down to my ankle as he pauses beside me.

I close my eyes for a second and let myself breathe. The horror of everything that's just happened hasn't even sunken in. I've just watched two people die—two people I was starting to consider my friends. It feels like it can't be real. How can someone die so suddenly? So quickly?

I tug at my foot again, pain throbbing through it as the rocks constrict around me—tighter and tighter.

When I lost my sister, it wasn't sudden. She knew it was coming. I knew it, too.

What did she think about? The days—weeks—while she waited. How did she get through that?

Maybe what happened to Elias and Star was merciful. Maybe they were the lucky ones, and America and I are the fools, left in limbo waiting and wondering when it will finally be our turn. The only thing we can do is keep running and buy ourselves more time, but for what? When there were four of us, it seemed like maybe there was something to fight for, but now, even if we do get out of this cave somehow, why? We have no purpose. No mission, other than to save ourselves and put off dying for another few hours, maybe another few days if we're lucky.

"Just leave me here, America," I finally say. "I'm a lost cause, but you can still get out. Get back to the starship or something. I don't know."

"Shawn, just breathe for a second," America says calmly.

"How can I breathe?" I cry.

In the distance, the monster moans. The cave shakes as it slams itself against the wall. It's too big to get through, but once it starts burrowing, we'll be done for.

"Shawn, look at me," America says.

I pinch my eyes shut for a second before turning them up to meet his. "We're going to get you out of this. I'm not going to leave you here. Your foot got in there somehow, so we can get it out, but you have to quit tugging on it. You're only getting it stuck more tightly."

I pause, letting the hot air in my lungs cool as I take in deep breaths.

He examines the rocks for a few seconds before taking my leg at the knee and sliding my foot forward. "Now, twist your ankle around," he says. "See if you can bend it back enough to pull it out."

I roll my ankle beneath the rocks, pointing my toe straight like a ballerina. Finally, I kick my foot forward slightly and ease it out of the gap between the stones.

When I feel the pressure on my bones release, I gasp a sigh of relief, sliding my foot the rest of the way out. I shake my leg out, my entire body quivering with fear and adrenaline.

Then, not knowing why I do it, I hug him. My eyes burn as I let tears sink into the fabric of his spacesuit. "Thank you," I whisper into him. "Thank you for not leaving me."

"I've got you," he says. He hugs me back, and the contact feels comforting. I'm not alone. I'm not alone.

"I'm not leaving you behind, Shawn."

The grunting of the monster in the distance pulls us back to reality, and we snap apart.

"Let's get out of here," America says.

I take my steps more slowly this time, making sure I have a firm grasp on each rock as we climb our way up through the tunnel. The stench of rot and decay lessens as we distance ourselves from the chamber. The further we go, the narrower the tunnel becomes. It constricts around us like a clogged artery.

After pulling myself up on a large rock, I reach back to give America a hand. He takes it, and I help him climb his way up.

"How much longer do you think this goes for?" I ask. My heart pounds from the exertion. I don't know how much further I can go without a break. "It seems like it's getting narrower. What if it just stops in a dead end?"

"I don't think it does." America points up ahead, and I turn to look. There, at the top of a steep, ten-foot incline, is a gap between the rocks. Starlight shines in through the opening in ghostly hues of twilight.

A smile spreads across my face for the first time in I don't know how long. "We made it!" I nearly laugh. "We're going to get out!" I grin as I turn to America. Even though I don't have a light anymore, I can see him smiling faintly in the dim starlight cutting through the opening above.

"You go up first," he says. "I'll give you a boost."

He cups his hands on the ground. I hesitate a second before planting my good foot on his palms. I rest one hand on his shoulder and brace myself with the other against the steep rocks at the edge of the tunnel. He raises me up towards the opening, and I turn, stretching my arms above my head. My fingertips graze against the rock ledge, but I can't get a firm enough a grip.

"Can you get it?" America calls up.

"It's just a little too far," I say.

He grunts, and then I'm hoisted another two inches into the air. I slam my hands down on the flat surface and dig my fingernails into the dirt. My muscles burn as I kick off, scraping the toes of my boots against the sides of the rocks for traction. I gasp as I finally leverage myself enough to pull my body out of the tunnel.

I stand and take a deep breath of fresh air into my lungs. Relief floods through me. The air is dry and cool. It's nearly odorless, unlike the rank, stifling atmosphere in the bowels of this planet.

I glance up at the clear sky. Even though it's the middle of the night, I can see clearly. Without any light pollution, the stars shine above us brighter than I've ever seen them from Earth. The entire atmosphere glows a grey, purplish hue, and the Milky Way smears like a soup of glitter, sparkling across the sky. We are four and a half light years from Earth, but home suddenly doesn't seem so far away. In the vast scape of the entire universe and the billions and billions of galaxies swirling through it, we've barely even stepped out our front door.

Pulling myself from the captivating scene, I look back down to America.

"Okay," I say. "I'm going to lean over as far as I can, and then you jump up and grab my hands."

I get down on my knees and flatten myself out on my stomach, stretching my arms out towards him.

He stands there for a second, looking up at me with a somber smile.

"Come on," I say. "This is it. We're almost out!"

"I think you should go on without me, Shawn," he says.

"What?" My heart skips a beat before slamming against my ribcage like it's trying to get out. "I'm not leaving you here! It's only a couple feet! You can jump, and if you can't reach, I'll find a rope or something back at the starship to pull you out. You didn't leave me. I'm not leaving you either!"

He glances off to his side, and his light flashes over his leg. For the first time, I notice the blood dripping from his thigh. A tear in his spacesuit reveals a small bite wound oozing on his skin. In the beam of his headlamp, something moves within it. Crawling.

"Oh my God," I whisper. My hands go up to cover my mouth. "One of them bit you."

He nods. "I don't know how much longer I have left before it . . ." His voice trails off. "I can feel it beneath my skin already." He pauses for a second, scratching at his leg before looking up to me. "I needed to make sure you got out, Shawn. I've done that now. It's time for you to leave me here."

"I can't." Tears burn my nose and sting behind my eyes. "I can't leave you."

"I can't come with you."

"I might be infected, too," I say. "My helmet snapped off halfway through while we were fighting those monsters. I'm covered in cuts. Something could have gotten in."

"Could have," America says, "but you don't know. You might be fine. Me . . . we know for sure. I'm infected."

"America." Tears run down my cheeks.

"I've done what I wanted to do, Shawn. I wanted to save you. I owed it to you." A pause. "I'm okay now. You have to leave me."

"But what am I supposed to do now?" I ask. "Even if I do leave you, I'm just going to be running until something finally catches me." The idea of spending my last few hours or days alone on this infected planet terrifies me. I'll have nothing to do. No reason to keep living, and nothing to think about other than dying. The thoughts themselves will drive me to my limits.

"I don't want to die alone out here," I finally say. I twist myself so I'm sitting with my feet hanging over the ledge. "If you can't come with me, then I'm coming back down with you."

I breath in heavily. It's a good fifteen-foot drop into the tunnel.

"Shawn, stop!" America shouts at me before I can build up the courage to push myself off. "Do you want to die a coward?"

I pause where I am. "Well how else am I supposed to die, America?" I shoot back. My tone comes out harsh and sharp, but tears blur my eyes. "There is nothing here for me to do. If I keep going, it will only be to save myself, and for no reason—just prolonging the inevitable."

"You have to find a reason, then."

"I can't do that!" I scream at him. "Don't you understand? We are four and a half light years from home." I throw my hand at the star-streaked sky. "Nothing I do could matter to anyone. I have no purpose."

"Nobody has a purpose, Shawn," America says. "We just find something that matters to us and make our own purposes."

"There's nothing here that matters to me." My voice comes out low and pathetic.

"What mattered to you before, then?" he asks. "I know what you did to go to prison, and I know you aren't a bad person, and you aren't a coward, either. You're a criminal, but you have a heart, Shawn."

I look away from him. I don't want him to see how much I'm crying.

"When I decided to go on this mission, I was taking a huge risk. I could have just been left in prison to rot for the rest of my life, but I faked that crime anyway," he says. "I did it because it was what I wanted more than anything else in the world. I wanted to go to space. It was my dream—my purpose."

I pinch my eyes closed. I think about Star. She committed murder, but she did it to save someone she loved. She did it for her mom. She did it for a reason, and she didn't regret it.

I think about Elias, and the story he told me after I woke up from my nightmare while we were waiting for the worm in the tunnel to pass. He did what he did to save his daughter, risking everything for someone he loved.

"This journey was nothing like what I thought it would be," America finally continues, "but nothing ever really is, is it? At least now I won't end my life wondering what could have been. I don't regret the decisions I made in my life. You know Star and Elias didn't, and I don't think you do, either."

I finally turn back to meet his eyes.

"Don't make your last decision one that you'll regret," he says.

We are both silent for a moment. My breath condenses in front of me as I listen to the sound of my own heart beating.

"So what am I supposed to do?" I finally ask.

"What did you want to do before?" America asks. "Why did you risk going to prison for your entire life? What was it that was so valuable to you?"

"I wanted to save people," I whisper. "That was it." I didn't know anyone I was helping, but it didn't matter. I've never been good with making friends—with personal relationships—but I do care about people. I want to save them.

America nods.

"But there's no one here to save," I say under my breath.

"But there are people on Earth," he says. "You're smart, Shawn. A hell of a lot smarter than me, that's for sure. Think about it. Our mission wasn't the first one sent to this planet. Even after what happened to the crew of our sister ship, Alexander, ICC let us land here. They let the same thing that happened to the crew of Alexander happen to us."

I'm quiet for a second.

"Why?" he asks. "Why did they let that happen?"

"Because they didn't know." My voice comes out as a hushed whisper. My entire body shakes with a combination of fear and anger. "The never found out what happened to the first mission. I have to warn them."

"Exactly."

"I can't let this happen to anyone else." I grind my teeth together, finally pushing myself to my feet.

America clicks the buttons on the side of his helmet, snapping it off his head. "Here." He tosses it up. It flies to me in a smooth arc, and I catch it. "I think you'll be needing this more than me."