Space Marines are sent to investigate strange events at a research facility on Mars but find themselves at the mercy of genetically enhanced killing machines.

Samantha Grimm: [about Carmack's transformation] It may even be reversible...
Sarge: It's irreversible.
Samantha Grimm: You don't know that...
Sarge: Doctor-Carmack's-condition-is-irreversible.
[turns to Carmack and raises his pistol]
Samantha Grimm: NO-!
[Sarge shoots Carmack]
Sarge: Because Carmack's condition is that... he's dead.
Sarge: I'm not supposed to die.
Pinky: You don't look like a "Mac".
Mac: Katsuhiko Kumanosuke Takaashi.
Pinky: So, Mac.
Sarge: Kill them all, let God sort them out.
Sarge: Pinky, do you see Portman?
[Pinky watches Portman being attacked by a demon on his gun-cam]
Pinky: No.
Sarge: Semper Fi, Motherfucker! Faithful to the corps John.
[after Sarge shoots Kid]
John Grimm: [shouting] It was his first mission!
Sarge: And it's not gonna be my last.
Sarge: Eliminate the threat.
The Kid: What threat?
Duke: It goes that this see, if its trying kill ya. Its a threat
Corporal Dean Portman: Ladies, we're under a Level 5 quarantine so I'm gonna have to strip search you girls.
Samantha Grimm: So, "Reaper"? As in "Grim"?
John Grimm: They're Marines, Sam, not poets.
Corporal Dean Portman: I don't believe this shit. Six months without a weekend, and the goddamn transporters are five minutes late. Now that's 5 minutes of R and R that I ain't gonna get back.
Duke: Relax baby, we're on vacation!
Sarge: [Talking about where the Imp came from] Is there anyway this thing came from the outside, on the surface?
Samantha Grimm: The planet is completely dead.
Corporal Dean Portman: It came from *some where*, lady.
Sarge: Portman, shutup.
Samantha Grimm: The atmosphere on the surface can't support life.
Corporal Dean Portman: Maybe it doesn't need air, it could've come from another planet or something.
Samantha Grimm: [scoffs] What, like an alien?
Corporal Dean Portman: LOOK AT THAT THING!
Sarge: PORTMAN, YOU NEED TO SHUT THE FUCK UP!
Pinky: Portman, I got floor and wall on your gun cam.
Corporal Dean Portman: I'm taking a shit, you fucking gimp.
Sarge: I didn't see shit. And I ain't paid to see shit.
Samantha Grimm: 10% of the human genome is still unmapped. Some say it's the genetic blueprint for the soul.
Female electronic voice: RRTS Special Ops clearance verified. Handle ID: Destroyer.
Destroyer: Daddy's home.
Female electronic voice: Handle ID: Mac. Handle ID: Portman. Handle ID: Goat. Handle ID: The Kid.
The Kid: "The Kid"?
Female electronic voice: Handle ID: Duke.
Duke: Say my name, baby.
Samantha Grimm: You know, Duke, I bet secretly you've got a big heart.
Duke: Oh, yeah? Well, that ain't the only secret big thing I got.
Samantha Grimm: Little rusty, huh?
Duke: [chuckles] Oh, lady, you have no idea.
Corporal Dean Portman: What the hell is that?
Goat: You never did time, Portman?
Corporal Dean Portman: What?
Goat: This is a holding cell.
Corporal Dean Portman: Bullshit. What makes you think that?
Goat: Touch it.
[Portman reaches out and gets shocked]
Goat: 'Cause the walls are electrified.
Corporal Dean Portman: You asshole!
John Grimm: [about the dead mutant's body] This is not what me and Goat shot at in Genetics.
Corporal Dean Portman: You mean there's more of these fucking things?
The Kid: Is it always that rough?
Pinky: Believe me, it used to be a lot rougher. There was a time when Ark travel was susceptible to, let's say major turbulence.
The Kid: What's he mean?
John Grimm: He means he went to one galaxy, his ass went to another.
Pinky: Call it a scientific miscalculation.
Corporal Dean Portman: [looks down the sewer hole] I thought "being in the shit" was a figure of speech.
Sarge: Get in the goddamn hole, Portman.
John Grimm: [fighting a mutated Pinky in first-person perspective using a chainsaw] COME ON, YOU MOTHERFUCKER! YEAH!
John Grimm: Like The Kid said, "Go to Hell"!
John Grimm: [approaching a mangled Scientist] Sir, are you okay?
[scientist turns to face him and bites the head off of a live rat]
John Grimm: Okay...
John Grimm: [hands Samantha a gun] If I turn into one of those demons, shoot me. One in the heart and one in the head, and don't you hesitate.
Samantha Grimm: [slowly takes the gun] I won't have to.
[after Sam closes the nanowall on a monster]
Duke: And that's why I don't do nanowalls.
Sarge: Nothing gets back till everything on this planet is dead. We're going in hot.
Samantha Grimm: Does it ever bother you, you could've spent your life looking in a microscope instead of a sniper scope?
John Grimm: If they were so smart, how come they're so dead?
[Before entering the lab]
Samantha Grimm: In one of the carbon dating labs, there was an internal telephone left off the hook.
Sarge: Did you get any information from it?
[Sam looks at Hunegs, who clicks on a small tape recorder: loud screaming]
Sarge: Open the door.
John Grimm: [walks through Genetics and sees internal organs on cages] Looks like we missed the party.
Sarge: [after unlocking Bio-Force Gun vault] Big fucking gun.
Duke: Where the fuck are we?
Goat: Couple a million light years from breakfast.
[repeated line]
Sarge: Portman, you need to shut up.
Corporal Dean Portman: I gotta take a dump.
Destroyer: What? Now?
Corporal Dean Portman: Unless you want me shitting my pants right here.
Goat: Be sober; be vigilant because your adversary the Devil walketh about seeking whom he may devour.
Corporal Dean Portman: That's real comforting Goat, that ain't freaking me out at all.
Sarge: How long's it been?
John Grimm: Ten years.
Sarge: You sure she's even still up there?
John Grimm: [nods] Yeah.
[pause]
John Grimm: I guess you got to face your demons sometimes.
[last lines]
John Grimm: Almost home.
Goat: God damn it!
[takes out a knife and carves a cross in his arm. He sees Reaper watching him]
Goat: I took His name in vain.
Sarge: Shoulder your fucking weapon, soldier!
Corporal Dean Portman: We don't know what we are dealing with here. Its S.O.P. to call reinforcements when its insecu...
Sarge: WE ARE... The reinforcements.
Sarge: [after pulling Portman out of the water] Portman, what the hell happened?
Corporal Dean Portman: I fell in the damn hole.
Sarge: Are you gonna shoot me?
John Grimm: Yeah, was thinking about it
Sarge: What you got left?
John Grimm: Half a clip. You?
Sarge: [points BFG] I've got one round.
Corporal Dean Portman: Five bucks says this shit ain't nothing but a disgruntled employee with a gun.
Corporal Dean Portman: I'm gonna lock myself in a motel room with a bottle of tequila and three she-boys!
[about the planet's extinct inhabitants]
John Grimm: If they were so smart, how come they're so dead?
Samantha Grimm: We don't know. Maybe they just went with time.
[John looks at the position of the skeletons]
John Grimm: You don't shield a baby from time.
Corporal Dean Portman: [talks to Destroyer while guarding the airlock door] This is bullshit, man. I enlisted to serve my country, not get greased protecting some corporation's goddamn science project.
Corporal Dean Portman: [talks to The Kid on the Helicopter while en route to the Ark] You know, Kid, it's funny. A couple of days ago I asked Sarge for a little pussy. The next day he brought you onto the team.
John Grimm: Don't give me an excuse, Portman. No one here will miss you.
Destroyer: [Destroyer lifts a gate off of a vent and shoots at something] Agh!
Sarge: What was it?
Destroyer: A monkey Sir. Some kind of monkey.
Sarge: We're gonna need something with a little bit more kick.
[first lines]
Samantha Grimm: [narrating] In the year 2026 archaeologists working in the Nevada desert discovered a portal to an ancient city on Mars. They call this portal the Ark. Twenty years later, we're still struggling to understand why it was built and what happened to the civilization that built it.
Sarge: [after shooting one of his men dead] I need soldiers. I don't need anyone else, but "soldiers".
Pinky: All right, drop the weapons! I mean it! I am not going to be killed by a madman, drop the weapons!
[something growls]
Pinky: Aw, there's something behind me, isn't there?
Duke: [after meeting Samantha] Please tell me you didn't let a fine piece of ass like that get away from you, Reaper.
John Grimm: She's my sister.
Duke: No shit?
Destroyer: Don't do this again, man.
Duke: Do what?
[after blasting a hole in the wall with the BFG3000]
Sarge: Holy shit.
Sarge: Listen up, men. Leave is canceled.
[Groans and murmuring from the squad]
Duke: [under his breath] Aw, man... I don't believe it. Fuck!
Sarge: You got a problem with that, Duke?
Duke: Me, Sarge? Hell, no! I love my job!