A small alien spacecraft drifts through the Solar System and, when it nears Earth, is struck by an asteroid, veering off course and crashing under the cover of night in the quiet town of Perry Hall. The crash is noticed by a pair of hunters who alert the county sheriff, Cinder, Donn Angelos. As locals begin to investigate, the pilot emerges from the wreckage and unleashes a deadly disintegrator ray, slaughtering the hunters and setting off a chain of fear and chaos. The beast then launches a stealthy attack on a couple in their home and on a family out for a drive, leaving destruction in its wake and forcing the town to confront an incomprehensible threat.
Cinder and his unit, joined by a handful of armed residents including a man named Jamie, close in on the creature. They quickly discover that the beast seems impervious to ordinary bullets, and their efforts cost them dearly as many fall to the disintegrator’s deadly reach. In a turning point, a skilled marksman arrives and, after a tense confrontation, fires shots that blow away the disintegrator and briefly render the creature vulnerable. The respite is short-lived: the marksman’s son and another officer perish in the ensuing shootout, underscoring the peril facing the town and its defenders.
With the threat intensifying, the police begin a coordinated evacuation of Perry Hall. Yet the political element complicates matters when mayor Bert Wicker refuses to cancel his party for governor Embry, insisting the celebration proceed. Amid the surrounding panic, a delinquent named Drago exploits the chaos, abusing his girlfriend who has been involved with Jamie. When the police come to order the evacuation, Drago slips away and returns to strangle the girl. Jamie, growing increasingly suspicious of Drago, takes action on his own and uses a dirt bike to confront him.
As more evidence of the beast’s power surfaces, Cinder and his deputy, Lisa, uncover a mutilated corpse and narrowly escape an ominous return by the creature. Cinder injures his leg during the escape, and Lisa helps him recuperate at her home, where the pair share a private moment. Back at Wicker’s looming party, Mary Jane—the mayor’s secretary—is also present, and the alcohol-fueled atmosphere masks the danger that stalks them all.
Meanwhile, at the office of Doctor Steven Price, the beast reappears and kills a few men. Price and nurse Ruth retreat to the basement and devise a plan to trap the creature using a frayed electrical cord, which successfully delivers an electric shock and drives the beast away. The body of Drago’s girlfriend is found and brought to Price; Jamie, convinced of Drago’s guilt, confronts him and administers a beating.
The showdown intensifies as Price is tasked with watching over Wicker and Mary Jane until evacuation can be completed. The beast nevertheless slips past, killing Mary Jane in the basement, and her screams rouse Wicker, who goes to investigate and meets a brutal fate. Cinder and his crew return to Wicker’s house with a plan to spring a trap: they thread metal wire between trees and connect it to a high-voltage coil in the power plant. Their aim is to discharge a lethal surge when the breakers are flipped.
The beast attacks out of nowhere, forcing Jamie to cling to the wire to keep the trap intact. As the breakers are thrown, a powerful current surges through the improvised wire coil and detonates the creature in a spectacular explosion. In the chaos, Jamie is pulled into the same blast and vanishes with the monster. The final image lifts toward the night sky, the stars unfurling overhead as the town faces the consequences of the encounter and the screen fades to black.
