Drive-In Massacre

A couple arrives at a rural California drive-in and is brutally attacked by an unseen killer. The man is decapitated with a sword, and the woman is skewered through the neck, establishing a violent pattern. The carnage sets the tone for the investigation that follows.

Detectives Leary and Koch launch the investigation into the murders and begin questioning the drive-in's manager, Austin Johnson, and the custodian, Germy. They search for leads, including a prowling voyeur and a possible license plate connection. The case escalates as more clues surface.

Germy explains that a peeping tom prowls the area, watching couples and single women, and he urges the detectives to record the voyeur's license plate. He provides a lead that could tie the killer to a specific vehicle and owner. The detectives weigh this information as a possible breakthrough.

The license plate leads to Orville Ingleson, whose home is searched and whose car yields a bloody cloth. Orville panics and tries to flee when confronted, but is captured. He claims the blood came from a dog he ran over, a claim later checked through analysis.

That evening, a detective (disguised as a woman) attends a screening at the drive-in and spots Orville despite his promise to stay away. A customer returns to his car after a confrontation and discovers his girlfriend beheaded. The scene confirms the killer is stalking the drive-in.

Leary and Koch rush to Orville's car and find him dead from a slit throat. His death abruptly ends one line of investigation, suggesting the killer is still at large. The detectives reassess potential suspects while the drive-in remains at risk.

Austin Johnson and Germy are brought in for questioning. Austin resists closing the drive-in without a court order and fires Germy, displaying hostility toward the police inquiry. The tension underscores the dangerous, unpredictable nature of the killer.

The next evening, the detectives pursue a machete-wielding man who has murdered two and taken a girl hostage at a warehouse. After a pursuit and stand-off, they shoot the man dead, only to learn he is a recent escapee with no serial connection.

Back at the drive-in, Germy confronts Austin about the sword collection and owed money as he enters the projection booth. The moment is interrupted when a silhouette of Austin is shown being killed with a sword on the screen during a Wild West film.

Leary and Koch break into the projection booth to find both Austin and Germy murdered, confirming the killer's ruthlessness and that the sword motif is central to the murders. The killer leaves no trace, deepening the mystery.

On-screen text reveals that other drive-ins across the country are being plagued by similar bloodbaths and that the killer's identity remains unknown. A fake public address warns the audience that a psychopath is loose in their own drive-in.

The conclusion leaves the killer unidentified, implying the threat will continue beyond the events shown. The drive-in audience is left with a chilling sense that the danger could strike anywhere.