Laserblast

A green-skinned man wanders the desert and is slain as aliens land and open fire. The pair of extraterrestrials disintegrate him, then return to their spacecraft. In their hurry they leave behind a laser cannon and a pendant that will connect to future events.

Billy wakes to find his mother preparing to depart on a trip to Acapulco, despite his protests. He heads to Kathy's house and is cautioned by Colonel Farley about meddling, while Chuck and Froggy hassle him and deputies ticket him for speeding. The day sets a grim tone for the teen's further troubles.

While wandering the desert, Billy finds the alien laser cannon and a mysterious pendant. He learns the weapon only works when the pendant is worn on his chest. He begins firing at random targets, drawn to the power but unaware of the consequences.

Aboard their spacecraft, the two aliens converse in an unsubtitled language with their leader, who orders them to return to Earth and recover the cannon. The plan sets in motion a remote pursuit of Billy. Their mission reconnects Earth with the mysterious device.

Billy and Kathy attend a pool party with friends, where Chuck makes unwanted advances toward Kathy. Billy spars with Chuck and Froggy to defend her, heightening tensions around him. The gathering foreshadows the violence that will unfold.

That night, Billy uses the laser cannon on Chuck's car, triggering an explosion that Chuck and Froggy barely escape. The reckless act reveals the weapon's deadly potential and the danger Billy now embodies. Lawful authorities begin to take notice.

Government official Tony Craig arrives to investigate the explosion and the broader desert incident. He informs the sheriff that news related to the events must not leave town, suggesting a cover-up or controlled information. The appearance marks official scrutiny of Billy's fate.

Billy develops an unusual metallic disc on his sternum and seeks medical help. Doctor Mellon surgically removes the disc and contacts Mike London to arrange evaluation. The medical procedure uncovers an extraterrestrial connection that will drive the plot forward.

That night, Billy, now green-skinned and deranged, attacks Mellon's car and kills him in an explosion. The next day, Tony investigates the wreckage and retrieves an unknown material, setting up a scientific inquiry into its origin. The material's inorganic nature alarms the investigators.

Billy resumes his rampage by violently attacking and killing the two sheriff deputies who harassed him earlier. The town descends into fear as he roams with the deadly weapon.

While sleeping beside his van, Kathy discovers the alien pendant and places it on Billy's chest. His skin turns green and his face becomes grotesque, triggering a violent assault on Kathy. She escapes and hides from his aggression.

Billy roams in a relentless rampage, firing at random; a small law-enforcement airplane opens fire but Billy destroys it. He also destroys Chuck and Froggy's car, killing them both in the chaos.

The two aliens land on Earth and begin actively searching for Billy. Tony questions Colonel Farley and Kathy about Billy's fate as authorities scramble to understand the occurrences. The alien presence intensifies the pursuit.

The aliens kill a hippie to steal his van and Billy drives to an empty city block to continue firing. Kathy and Tony confront Billy as an alien fires a ray from a rooftop, killing him. The laser cannon and pendant are destroyed, and the aliens depart with their spacecraft.