Doom

The Ark

Year 2026. Deep below the Nevada desert, scientists discover the Ark—a wormhole portal providing instantaneous transportation to an ancient city on Mars. The discovery revolutionizes space travel and enables humanity to establish research facilities on Mars without requiring lengthy interplanetary journeys.

Twenty years later, in 2046, the Union Aerospace Corporation (UAC) operates a research facility on Mars staffed by 85 personnel conducting experiments in anthropology, archaeology, and genetics. The facility is suddenly attacked by an unknown assailant or assailants. The attack is severe enough that Dr. Carmack, one of the facility's scientists, sends a distress call to Earth requesting emergency assistance.

In response to the distress signal, a squad of eight elite marines is assembled and deployed to Mars. The team includes: Sergeant Asher "Sarge" Mahonin, the squad leader; and soldiers nicknamed "Duke," "Goat," "Destroyer," "Portman," "Mac," "Kid," and John "Reaper" Grimm. Their mission is search-and-destroy—locate survivors, eliminate threats, and secure the facility. UAC corporate leadership is primarily concerned with retrieving computer data from their experiments rather than rescuing personnel.

The marine squad uses the Ark to travel instantaneously from Nevada to Mars. Before departing, they order the Earth-side Ark facility placed on lockdown to prevent anything from using the portal to reach Earth while the Mars situation remains unresolved.

Arriving on Mars

Upon arrival on Mars, the marines are met by "Pinky," a UAC employee confined to a wheelchair. Pinky provides the marines with facility information and access to restricted areas.

Reaper discovers his twin sister, Dr. Samantha "Sam" Grimm, works at the facility as a scientist. Reaper escorts Sam to secure locations where she can retrieve the experimental data UAC wants recovered. During their time together, Sam explains recent developments at the facility: a dig site was reopened after being closed for years following an accident that killed their parents, who were also scientists working on Mars. The dig uncovered ancient skeletons belonging to a humanoid race that predated human civilization on Mars.

The critical discovery was that these ancient Martians had been genetically enhanced with an artificial 24th chromosome pair—a genetic modification far beyond natural evolution that granted them enhanced capabilities.

First Casualties

While searching the facility for survivors, the marines locate Dr. Carmack, who is severely traumatized and injured. They escort him to the medical laboratory for treatment. However, Carmack later disappears from the medical area under mysterious circumstances.

During exploration of the genetics laboratory, the marines encounter an unknown creature. They pursue it into the facility's sewer system, where the creature ambushes and kills Goat. The remaining marines manage to shoot and kill the creature, then transport its corpse to the medical lab for examination.

Sam performs an autopsy on the dead creature and makes a horrifying discovery: despite its monstrous appearance, its internal organs are human. The creature was once a person who worked at the facility.

While Sam and Duke are in the medical lab, they witness Goat resurrecting from death. The reanimated Goat immediately demonstrates violent psychosis, killing himself by repeatedly smashing his head against a reinforced window until his skull fractures. Sam and Duke are then attacked by another creature, which they eventually identify as a mutated Dr. Carmack—the injured scientist they rescued earlier has transformed into one of the monsters.

The Hunt

The marine squad systematically tracks down and destroys multiple creatures throughout the facility. However, the hunt costs them heavily: Mac, Destroyer, and Portman are all killed during encounters with the mutants.

Sarge kills the creature that was once Dr. Carmack in a violent confrontation fueled by anger over lost squad members.

Sam, Reaper, and Sarge piece together what happened at the facility. UAC was conducting experiments on human subjects using the extra Martian Chromosome—designated C24—which was harvested from the remains of the ancient Martian skeletons. The experiments were attempting to replicate the genetic enhancement that gave the ancient Martians superior abilities. However, the test subjects infected with C24 transformed into monsters and broke free of containment, creating the outbreak that killed or mutated most of the facility's personnel.

Sam and Reaper try to convince Sarge that not everyone infected with C24 will become a monster. Sam hypothesizes that the chromosome's effects depend on the subject's inherent nature: people with violent tendencies, psychotic predispositions, or evil inclinations transform into creatures, while inherently good people injected with C24 develop superhuman abilities but retain their humanity and moral character.

Sam believes this same pattern occurred with the ancient Martians—some became enhanced superhumans while others became monsters. The monstrous Martians may have triggered a catastrophic war or outbreak, forcing the survivors to build the Ark as an escape route to flee Mars.

Earth Breach

Some of the creatures discover and use the Ark to travel through the wormhole to Earth. At the Nevada facility, the creatures slaughter or infect the research staff, creating a second outbreak site.

The marines, Sam, and Pinky follow the creatures through the Ark back to Earth to contain the threat. Sarge, becoming increasingly unstable and ruthless, orders the squad to "sanitize" the entire facility—killing everyone, including survivors, to prevent any possibility of the infection spreading beyond the containment zone.

When Kid discovers a group of uninfected survivors hiding in the facility, he reports their location to Sarge but refuses to kill innocent people. Sarge executes Kid for insubordination, shooting him for disobeying the sanitization order.

The execution creates a standoff when Pinky, horrified by Sarge's murder of Kid, aims his weapon at Sarge. Before the confrontation can escalate into firefight between surviving squad members, creatures attack the group. The creatures kill Duke and drag both Sarge and Pinky away to unknown locations. During the chaotic fight, Reaper is wounded by a ricocheting bullet.

Transformation

Reaper is bleeding severely and will die from his wounds without immediate intervention. Sam makes a desperate decision: she injects her brother with the C24 serum, gambling that Reaper's inherently good nature means he will gain superhuman abilities rather than transforming into a monster.

Reaper loses consciousness from the injection. When he regains consciousness, his wounds have completely healed. However, Sam has disappeared while he was unconscious.

Using his newly gained C24 superhuman abilities—enhanced strength, speed, reflexes, and durability—Reaper fights through the facility searching for Sam. He battles numerous creatures, including a horrifically mutated version of Pinky, whose transformation has made him far more dangerous despite his previous disability.

Final Battle

Reaper finds Sam unconscious. Standing over her is Sarge, who has become infected with C24. Unlike Reaper, Sarge's violent nature and increasingly unstable psychology meant that C24 transformed him into a superhuman monster rather than an enhanced hero. Sarge has killed the group of survivors that Kid had refused to execute earlier—the innocent people Kid died protecting.

Reaper and Sarge, both enhanced with superhuman C24 abilities, engage in a brutal fight. Sarge's transformation has made him enormously strong and savage, but Reaper's retained humanity gives him focus and determination that Sarge's monstrous rage cannot match.

Through sustained combat, Reaper gains the upper hand. He throws the transformed Sarge backward through the Ark portal, sending him back to Mars. Reaper throws a grenade through the portal immediately after Sarge. The grenade explodes on the Mars side, destroying both Sarge and the Mars research facility, eliminating the source of the C24 outbreak and preventing any further creatures from using the Ark.

With the threat neutralized, Reaper carries his unconscious sister Sam into an elevator. They ascend toward the surface, leaving behind the horror of the facility and the alien infection that nearly destroyed humanity.

The ending validates Sam's hypothesis that C24 amplifies inherent nature rather than randomly transforming people, suggesting that superhuman power reveals and intensifies existing character rather than creating it. Reaper's heroic use of enhanced abilities contrasts with Sarge's monstrous transformation, demonstrating that the chromosome was not inherently corrupting but rather acted as a moral amplifier that exposed what people truly were beneath social constraints.

The destruction of the Mars facility and Sarge simultaneously eliminates both the source of the outbreak and the most dangerous infected individual, providing clear resolution while also ensuring the C24 experiments cannot continue. The ending suggests that some scientific knowledge is too dangerous to pursue, and that attempting to artificially enhance humanity through alien genetic material inevitably unleashes the worst aspects of human nature in those predisposed to violence.

Reaper's survival and retention of his C24 abilities creates an ambiguous conclusion about whether the enhancement is entirely eliminated or whether Reaper now exists as an enhanced human with responsibilities for protecting others using his powers. The film ends before addressing whether Reaper's abilities will fade, become permanent, or require further intervention, leaving his status as potentially the first successful superhuman unclear.

Sam's unconsciousness prevents her from witnessing or confirming the success of her hypothesis, suggesting that scientific validation is less important than practical results—her theory was correct because Reaper remained human, but she cannot collect data or publish findings. The ending prioritizes survival over scientific achievement, implying that some experiments should end with all records destroyed rather than preserved for future research.

The film ultimately argues that humanity is unprepared for certain types of enhancement and that attempting to transcend natural limitations through alien biology will inevitably create monsters because most people cannot handle the amplification of their worst traits. Only exceptionally moral individuals like Reaper can be trusted with such power, making widespread enhancement impossible without catastrophic consequences.

Is Doom based on the video game?

Yes, the film is adapted from the Doom video game series, though it significantly alters the source material's plot. The games focus on demonic invasion through portal technology, while the film changes demons to genetically mutated humans infected with an alien chromosome. The film retains some game elements like the Mars setting, portal technology, and monsters, but creates an entirely new story rather than directly adapting game narrative.

What is the C24 chromosome and how does it work?

The C24 chromosome is an artificial 24th pair of chromosomes discovered in ancient Martian skeletons and replicated by UAC scientists for human experimentation. The film suggests it amplifies inherent moral character: good people gain superhuman abilities while retaining humanity, while violent or psychotic people transform into monsters. The biological mechanism is not scientifically explained, functioning as a moral detector rather than following real genetic principles.

Why did Sarge become a monster while Reaper remained human?

The film establishes that C24 transformation depends on pre-existing moral character. Sarge's increasing ruthlessness throughout the film—executing Kid, ordering the killing of survivors, embracing "sanitization" over rescue—demonstrates a violent nature that C24 amplified into monstrous transformation. Reaper's consistent protection of innocents and moral restraint meant C24 enhanced him without corrupting him.

What happened to the ancient Martians?

The film implies the ancient Martians experimented on themselves with C24, creating a civilization of enhanced beings. However, those with violent tendencies transformed into monsters, triggering a catastrophic outbreak or war. The survivors built the Ark as an escape route, possibly fleeing to Earth or elsewhere. The film suggests the Martian civilization destroyed itself through the same genetic experiments UAC later repeated.