"Holy shit," Star gasps. She takes a step back from Devin.

My stomach turns with nausea, and I grit my teeth.

"Devin, are you okay?" America asks. He reaches a shaking hand out to him before drawing it back and taking a step away.

Devin coughs again, and then he reaches to his mouth. Grimacing, he pulls another tooth from his upper jaw. He gags as the incisor releases with a pop, a trail of blood running like a cord back to the roof of his mouth.

"Do I fucking look okay to you?" Devin swats the sticky red string away as he shoots a glare at America. He pinches his eyes shut for a second. When he opens them, lines of translucent, reddish-brown tears run from their corners like rusty water leaking from a pipe.

A guttural scream releases from his throat. He throws the teeth to the ground and reaches to his eyes with clawed fingers, pulling at the lower lids. The streaks of rust thicken, and their color deepens to vermillion.

Blood.

"Oh my God!" Devin cries. His hands shake as he scratches at his skin. "What the fuck is happening to me?"

America grabs me by the wrist. His fingers tighten around the sleeve of my space suit, and he yanks me back. My pulse races, throbbing in my temples. My legs shake beneath me.

"What the fuck?" Devin moans as blood leaks from his eyes. He staggers back a few steps. He loses his balance and stumbles off to the side, bracing himself against the wall of the cave to keep from falling.

A cough shakes through his diaphragm, and his entire body shudders. His mouth gapes into a silent, pained howl. The remaining teeth in his upper jaw hang loose, ready to release. Within one of the bleeding holes in his skull where a tooth once was, something twists and squirms. A tiny spiral worm wriggles its way out like a maggot crawling through raw meat. A second one follows, inching its way between the tiny bubbles of blood and saliva.

My breath stops in my lungs. The entire cave freezes. The only sound that remains is Devin's pained panting.

He inhales heavily, and then a roar of anguish explodes from his throat. The scream pounds through the cave, echoing down the maze of tunnels. His head snaps around. Blank, empty eyes focus in on America and me. Even though my light shines directly into his eyes, his pupils dilate to the point that his irises disappear. Lines of bloodshot capillaries spiderweb out across the whites to the corners.

His bloody tongue runs over his remaining teeth. One of his canines loosens, swinging back and forth twice before releasing and falling into his mouth.

He doesn't even flinch. Instead, with a gulp, he swallows it like a pill.

"Devin," I gasp.

He takes a shaking step towards America and me. His bloody eyes are empty. His jaw stretches wide. Worms squish their way out from the holes in his gums, crawling between his teeth.

The pain in my ankle barely registers as I take another step back.

"Devin," America says, his voice tense. He holds one shaking hand out in front of him, like he's trying to get a rabid dog to stay. He releases his grip from my wrist, raising that arm in front of me and forming a protective barrier.

Devin bares his remaining teeth at us. He lets out a single barking croak, and he charges.

I scream.

He collides with America and me, knocking me to the side with his elbow as he grabs America by the shoulders. My injured ankle buckles beneath my weight, and I fall. My hip strikes the rocky floor of the cave, sending pain shuddering through me.

"Devin!" I yell. I try to push myself up, but my leg shakes too much. I can't stand. My entire body is weak with pain.

"Get the fuck off me!" America screams. He slams his hands into Devin's shoulders and shoved him back.

Devin plants one foot behind him to steady himself. Barely missing a beat, he lunges in again, throwing his entire weight forward. His fingers claw at the exposed skin of America's neck.

"Get off him!" Star yells. She dives in towards them, clawing at Devin's massive arm and trying to pull him off. She leaps onto his back. Her legs wrap around his waist as she throws her fist into the side of his head.

Like he's swatting a fly, Devin swings his arm back. His elbow clocks her in the side of the shoulder. The momentum tosses her towards the ground, but she doesn't release her legs from his waist. He tumbles down on top of her.

"Shit!" she growls as his massive body crushes her. "Get off me!" She shoves at him with both hands, but he's too heavy. She kicks her feet next, but he turns towards her and grabs on to one of her ankles.

"Hey!" America shouts at the Devin. "Over here!" Devin pauses for just a second to look at America, but it's all he needs. He rushes in towards him dives at his head with both hands extended in front of him, knocking him off to the side.

Together, America and Star beat Devin back. He barks and caws, releasing a guttural throat noise as they back him towards a corner. He glances between the two of them, and then he charges at America again.

"Let go!" America yells as his feet skid across the ground, struggling to gain traction. He wrestles to get out of Devin's grip, yanking at his wrists, but Devin is stronger. The guy is built like a brick shit house. He must have at least fifty pounds on him.

"Devin, over here!" Elias shouts.

Before Devin has time to react, a rock the size of a golf ball flies through the air, smacking the side of his jaw. The blow dislodges two more teeth from his mouth. They tumble to the ground, glittering wet and red in the light from my headlamp before clattering across the ground and disappearing in the shadows.

A pained croak escapes Devin's throat. The monster he has become releases his grip on America. He swings his arms around, curling his hands into tight fists, and charges at Elias and Star.

"Look out!" I scream.

The two leap in opposite directions, barely making it out of the monster's way in time. He skids to a stop, kicking up a plume of dirt. Through the dust, his head swings around, and he glares at America and me like a raging bull, his nostrils flaring.

"Devin, stop!" Elias yells, but it's useless. Devin isn't there anymore.

I scramble back, ignoring the pain in my ankle. Devin runs at us, but he isn't interested in me. He goes right for America's neck again, his mouth gaping like he's preparing to bite him with his few remaining loose teeth.

He knows America is the easiest target. He doesn't have a helmet on. He's the only one of us with exposed skin.

America throws his arms up to hold Devin back. As he struggles against him, something in the monster's mouth catches the light of my headlamp. Beneath a pocket of blood and squirming worms, something sharp and ridged protrudes from the hole where he lost a tooth. For some reason, I'm reminded of the tiny spiral shells I used to find at the beach, and the little creatures within digging their way into the sand as waves crashed over them. I'm reminded of the shell I found on the beach, the last Ike I saw my mom before leaving for this mission.

It's almost like a shell is growing out of Devin's gums.

Another tooth?

But how?

"Help!" America screams. The monster Devin has become swings its head forward, diving in for a bite.

My pulse races as my breath catches in my throat. Without thinking, I charge at the two of them. Devin's twice my size, but I can't stand back and do nothing anymore. I leap into the air, slamming the front of my helmet into his face with all of my weight. The sound of something crunching reverberates through the glass face shield as blood explodes across it in a gooey splatter.

An arm shoves me, and I fall on my ass. Within the ooze of blood covering the glass of my helmet, a few lone worms wriggle. I gag. Through a film of red, Devin glares down at me. His nose is crunched in and broken. Blood mixed with snot runs from it. It coats his lips and dribbles down his chin, but he doesn't stop. He shakes his head once, flinging a mixture of saliva, blood and snot through the air, and then he goes in after America again.

"Get the fuck off him!" Star bellows. She rushes towards them, scooping up the helmet Devin flung to the side as she does. She swings it behind herself, and then she whips it around and cracks him on the side of the head with it.

The sound pounds and echoes through the tunnel. Devin lets out an animalistic yelp as he falls to the ground. Star doesn't hesitate another second. She raises the helmet above her and slams it down on his head again.

And then again.

"I'm sorry, Devin," she hisses. She raises her foot above his convulsing body and stomps on his neck. There is a hollow crack, and his body goes still. His neck is caved in a soaked in blood. His head looks like a pumpkin that's been bashed in. Blood leaks from his cracked temple, sealing into the ground beneath him.

The entire tunnel is silent. The only sound is America's heavy panting. I'm frozen, too afraid to move. My arms and legs shake.

"Is he . . ." I finally say.

"Dead," Star finishes my sentence when I trail off. "Yes."

I wipe blood from the glass in front of my eyes. The two worms that lodged themselves onto my helmet squish beneath my gloved hand. Small trails of black, oily goo leak from their crushed bodies.

"What the fuck just happened?" America finally gasps. His hands shake as he clenches and releases his fists. "I can't see. Someone tell me what's going on."

"Did he bite you?" Star snaps.

America grimaces. "No. I don't think so." He runs his hands over his arms and legs like he is trying slick a swarm of fire ants off him.

"Did any of them get on you, America?" Elias asks. "In your mouth? Nose? Eyes?"

"No." America's voice shakes.

Elias approaches, scanning America for signs of movement. "There. On your neck." He points to his right shoulder.

America nearly jumps, and his hand goes to his neck like he is swatting a spider. He yanks a small worm from the collar of his spacesuit and flings it to the ground.

Elias stomps on it.

"Are there any more on me?" America's gaze darts around and he runs his hands across his body, frantically checking for anything squirming on him.

We are all quiet for a minute.

"I don't see anything else," I finally say.

Star clenches her left hand in a tight fist, still gripping Devin's helmet in her right one. She shoves it into America's chest. "Put it on," she says through gritted teeth. "Now. And don't fucking take it off, or I swear to God, I will kill you."