Refusing to believe her story about cave-dwelling monsters, the sole survivor of a spelunking exploration gone horribly wrong is forced to follow the authorities back into the caves where something awaits.

Vaines: What are those things?
Juno: Death.
Greg: Could piggyback on the elevator cables.
Ed Oswald: You planning to go down there, why not go down in style?
Greg: What, this old shit still works?
Ed Oswald: Sonny, let me tell you, this old shit-bucket will be working long time after that MP3 of yours.
Ellen Rios: [Ellen was recording herself to her little daughter] Hi, baby girl. Hi ya. It's Mommy. I... I just wanted to let you know... That I love you. I want you to be good... and kind... and caring. I want you to be a good person. You're so special, baby. Te quiero, te extrano, baby.
Sarah Carter: Those things were coming for us, so I hurt her so I could get away.
Vaines: [to the hospital doctor] There are five girls missing, and you put the one person who knows where they are to sleep?
Doctor Payne: Blood found on Sarah Carter's clothes: A positive. Blood type for Juno Caplan: A positive.
Ed Oswald: My granddaddy used to work down there. One time, him and two of his buddies broke into a whole new cave system. Really big. Company bosses figured there should be some rick picking to be had, so they sent my granddaddy back down to have a look-see. He never come back. Folks reckoned they must've broke clean through into hell. The devil was mighty pissed.
Sarah Carter: Everything you just said, you tell it to her face. We're not dead yet.
Cath: Is it okay?
Dan: You know what's good? Modern mines have metal props. Miners prefer these old wooden ones.
Cath: Why's that?
Dan: The metal ones don't give you any warning when they're about to go.
[first lines]
Ed Oswald: Jeez!
Greg: Hey, you want to share a sleeping bag?
Cath: [sniff] What's the cologne you're wearing? Yeah, six hours of sweat and dirt and all other kinds of shit. I think I'll pass.
Dan: Fuck! Fucking trigger-happy Americans.
Ellen Rios: Dan.
Dan: Fucking only answer they've got to anything is a fucking gun!
Ellen Rios: Dan, don't let her hear you this way.
Dan: There's a fucking ton of rubble between us. She couldn't hear a fucking rock concert.