Lee Custler, played by William Katt, is a journalist out for a jog when a bright object streaks across the sky and crashes nearby. Sheriff Armstrong investigates, and the pair head to the crash site, where they discover an abandoned caravan looming near the wreckage. From inside the wreckage, an Alien emerges and gives chase. Lee sprints back to his car, but Armstrong trips, falls, and is killed by the pursuing creature before it vanishes. A frightened Tammy finds Lee, and the two attempt to call for help, only to have their car destroyed by the Alien.
They hurry to a nearby café where they meet Hilary, played by Dedee Pfeiffer, as Hilary, along with Javier, Figgus, and Marcy, who remain skeptical of their story. After a tense exchange, they head back toward the crash site and discover Garrison wounded and the other passenger missing. The Alien reappears and kills Marcy, and while the others flee, it clashes with a cyborg-like Hunter. The group decides to seek safety with Valentine, the local hunter, traveling through the sewer system. All except Javier reach Valentine's residence, where his daughter Freckles, played by Jennifer Couch, waits. They call for a small paramilitary support unit, and Valentine, though badly tested, survives his confrontation with the Hunter and steels himself for what comes next.
The team then splits: Valentine and Lee head to meet the paramilitary force, while Tammy, Hilary, Freckles, Garrison and Figgus try to escape through a maze of tunnels. Garrison becomes separated and is killed by the Alien, leaving the others to reach the Hunter’s ship, where they discover a second Alien that is nearly dead. They realize that to rid themselves of the Hunter, they must kill the surviving Alien and seize a ray gun from the ship. Lee and Valentine later locate Two Fingers, Marty, and Styles—the paramilitary group—and search for T and Lexin, who are in the woods, only to find they are already dead. The Hunter kills Marty and Styles, and then kills Valentine while attempting to strike down Lee.
As the survivors regroup, Figgus is impaled on a branch and dies. Two Fingers makes a desperate attempt to kill the Hunter but is himself slain, along with Freckles. In a final push, Lee uses the ray gun on the Alien, triggering a massive explosion that obliterates the creature. The remaining trio—Lee, Hilary, and Tammy—make their way back toward town. Back aboard the Hunter’s ship, the masked hunter removes his helmet to reveal that he is a human from Earth, implying this is a similar, but not identical, world. The film ends with him remarking on the possibility of a second hunt.
