Set in a remote desert, Alex, Joanne, Frank, Larry and Rob work in an underground nuclear facility to push reanimation experiments toward creating a superhuman. Their subject, Thor, is a specimen drawn from a suicide found in the barren sands, and the team hopes to coax life back into him. When Thor is brought back, an uncontrollable creature surges to life, shattering the team’s plans and threatening everyone nearby. The next morning, Stockton, one of the project’s former overseers, is contacted by [Alex] at his home, and after a tense argument, Stockton decides to fly to the facility. He is joined by his son Scott, his daughter Wendy, and Wendy’s boyfriend Mark.
As soon as Thor returns to action, he murders [Frank] and [Larry] in the test room, leaving [Alex], [Joanne] and [Rob] to improvise their escape. [Alex] even erases his own handprint at the exit in a desperate bid to keep Thor alive, but he is pulled into the vents before he can leave. [Joanne] and [Rob] comb through old blueprints to locate another exit, yet misfortune strikes when [Rob] is killed while trying to rewire the power, leaving [Joanne] to face the nightmare alone.
Meanwhile, [Stockton] and the others arrive and enter the facility. A troubling truth emerges: Thor is mutating, and his survival now depends on sterols pulled from the brainstem, a discovery that adds a new, terrifying dimension to the project. Thor’s mortality mechanism becomes more grotesque as he sprouts a living pincer from his mouth and uses it to seize [Alex]’s sterol, killing him in a brutal act that marks the unleashing of his full danger.
The group splits up to minimize risk. [Wendy] experiences a sharp shift in perspective when she learns the extent of her father’s involvement, and she storms off with [Mark] in pursuit. [Stockton] goes to locate the scientists, while [Scott] remains in the rec room. The grim search leads [Stockton] to [Larry]’s body, and he then begins guiding the others toward an escape. Thor slips into the rec room and nearly takes [Scott] before the blare of a microwave timer outages his threat, giving Stockton a narrow chance to pull [Scott] to safety. The survivors finally meet [Joanne] and, together, they piece together the full picture of what happened inside the facility. When they attempt to escape, Thor closes in on them, dragging [Stockton] into the vent shafts and continuing his mutation, a sequence that foreshadows the escalating danger.
A shocking turn comes as Thor targets the others, killing [Joanne], [Mark], and [Scott], and then pressing on toward [Wendy]. In a moment that feels dreamlike, Wendy appears to sprout a pincer from her mouth, a vision later revealed to be a dream of Thor’s—an ominous sign of the creature’s reach into the minds and bodies around it.
Desperation drives a plan: the survivors decide to lure Thor into a freezer by laying a trail of sterols, hoping to entomb him. The gambit nearly succeeds, but Thor retaliates by taking down [Mark]. [Joanne] manages to shove Thor into the freezer, but with the facility’s hand code system down, escape seems impossible. They discover that [Stockton] is still alive and manage to use his handprint to unlock a way out. They flee, but Thor stows away on their plane and ambushes them again before departure.
In a fierce final struggle, [Scott] uses a shard of glass to sever Thor’s pincer, preventing a deadly strike, and the survivors reach the security of the aircraft. [Joanne] fires a shotgun, forcing Thor to topple away as the plane takes off toward safety. The craft accelerates into the sky, and for a moment, Thor lies motionless on the ground outside the plane. A last tremor—an anxious twitch of a hand—reveals that the threat may still survive, hinting at a lingering danger beyond the escape.
