Doom
The film is set on Mars in the year 2046, in the Union Aerospace Corporation (UAC)-owned Olduvai Research Facility where scientists are running for their lives. One by one, they are caught and pulled screaming into the darkness by some unseen monster. Carmack (Robert Russell), escapes into a sealed room and sends an SOS rescue signal warning about a Level 5 security breach in the top security lab. While he is saying this the door behind him is being torn open. He turns around and sees something through the gap in the door.
On Earth, a team of eight Marines have their leave interrupted by Sarge (Dwayne Johnson), who has received a call from Olduvai. The Mars station is immediately quarantined and the 85 UAC employees on Mars are not allowed to return to Earth. As the men suit up, Sarge pulls aside one of his men, John "Reaper" Grimm (Karl Urban), and asks him not to go because his sister is on the station. Reaper suits up anyway, and their team is deployed to Mars via a teleportation device called the Ark, located at Area 51. The Ark was discovered in 2026 (as told by opening credits narrator Rosamund Pike), and for twenty years scientists have been trying to discover who built it, and why. Upon arriving at the Mars research facility of the Union Aerospace Corporation (UAC), they meet an early victim of the Ark system, Pinky (Dexter Fletcher), who "went to one galaxy while his ass went to another" (his lower torso now a 2-wheeled engine resembling a Segway) during an Ark teleportation event. They meet up with Dr. Samantha Grimm (Rosamund Pike), Reaper's sister, who explains the situation.
Their mission is simple: eliminate the threat, secure the facility, and retrieve UAC property. John converses with his sister and learns that they have discovered humanoid remains on Mars that contain a 24th chromosome that made the creatures superhuman, invulnerable to disease and with the ability to heal from injuries near-instantly. They set off and quickly locate Dr. Carmack, who is mentally deranged to the point of tearing off his own ear. They return him to the lab, and Dr. Grimm tries to sedate him. Meanwhile, the Marines continue to explore the facility, encountering strange creatures intent on killing them. One of the creatures, an Imp, succeeds in slaying Goat (Ben Daniels), but is promptly killed and brought to Dr. Grimm. From blood samples taken from two hostile creatures, it is revealed that the things used to be human. Dr. Grimm determines that their genetic makeup has been altered by the addition of the Martian 24th chromosome; however, the injected chromosome seems to "choose" whether it causes the person to be superhuman or a monster, apparently able to determine on a genetic level whether a person has the capability to be truly evil. Consequently, the chromosome is classified as an infection, which is later spread by the projectile tongues of those infected. The Marines discover that Dr. Carmack deliberately injected the chromosome into an "evil" subject (prisoner Curtis Stahl, a multiple murderer), who later transformed and broke loose.
Through multiple attacks by the Imps, the squad is reduced to just Sarge, Reaper, The Kid (Al Weaver), Duke (Raz Adoti) and Dr. Grimm. The surviving team members realize that despite their best efforts, a Hell Knight has escaped through the Ark to the Earth due to Pinky's refusal to trigger a grenade Mac left with him to destroy the Ark. Before leaving, Sarge takes the Bio Force Gun (a stylistic reincarnation of the BFG 9000 of Doom fame), dubbing it the "Big Fucking Gun," as an in-joke (the generally accepted meaning for the acronym in the Doom games).
On Earth, the group finds the UAC facility full of bodies. Sarge orders his men to kill anything alive in order to prevent the infection from spreading. The Kid finds a group of living, non-infected humans and reports this to Sarge. The Kid resists Sarge's order to kill the civilians and is promptly executed by Sarge for insubordination. Pinky reappears, aiming a pistol at Sarge, but is dragged off by a monster.
Zombies attack, killing Duke and dragging Sarge through a malfunctioning bulletproof screen. Reaper is hit by a ricochet. To save his life, Samantha injects Reaper with Chomosome 24. Instead of becoming a monster, Reaper awakens as a superhuman, with all the enhanced strength and healing abilities that come with it.
Following Reaper's transformation and the discovery that Samantha is missing, the movie takes on a first-person shooter perspective, reminiscent of the game on which the film is based. In a span of a few minutes, Reaper slays an array of monsters, including Pinky, who has mutated into, appropriately enough, a Demon, commonly referred to by fans as "pinkies".
Switching back to a standard camera angle, Reaper emerges at the exit of the facility. Bodies are scattered everywhere, and a melted blue hole in the wall, the mark of a BFG blast, is still cooling. Near this hole, Reaper encounters Sarge and an unconscious Dr. Grimm lying on the floor. Reaper asks Sarge what happened to the non-infected survivors, to which he casually replies that he "took care of that problem". Reaper then notices the same injury on Sarge that Dr. Carmack had before he turned into a Imp, something Sarge has been hiding up til this point. After a badly injured Dr. Grimm crawls to safety, the two Marines face off. After ineffectively using the last of their ammunition, the two engage in hand-to-hand combat, which favours Sarge. As Sarge holds Reaper by the neck against the wall, a closeup up of Sarge's eye shows it becoming blood-shot. When the camera zooms out, Sarge is shown further transformed, with demonic features such as prominent skull structure, sharp teeth and red eyes. Reaper prevails by throwing Sarge into the Ark, followed by a ST grenade. Sarge and the Ark are obliterated. Reaper then retrieves Sam, who is just visibly conscious but unable to stand or walk, and holds her in his arms as he uses the elevator to return to the Earth's surface.
