Slumber Party Massacre III

A group of friends play volleyball on a sunny Venice Beach. The mood is light as they plan a sleepover for that night while Jackie notices her parents are out of town. Morgan, a quirky neighbor, tells Jackie he might buy the house once the family moves.

After the beach, Sarah climbs into her car and is brutally murdered by an unseen assailant using a power drill. Her death hints at the danger shadowing the group outside the house. The crime occurs off the main gathering, near the street.

Jackie arrives back at her house and encounters her odd neighbor Morgan, who wants to tour the inside. He mentions considering purchasing the property once the family moves. The moment adds a unsettling note as an unseen killer remains at large.

That night, Jackie's friends Diane, Maria, Juliette, Janine, and Susie arrive for the planned party. The house fills with chatter and plans for the evening, but a creeping sense of danger threads through the upbeat atmosphere.

Three boys, Frank, Tom, and Michael, show up and initially scare the girls. Jackie scolds them and tells them to leave, but Ken appears behind them, signaling the killer has entered the scene. The party's atmosphere shifts from playful to tense.

Michael goes to apologize to the girls and encounters the masked killer. He is killed by a brutal strike with a weapon, establishing the killer's deadly reach inside the house. The group realizes the threat is very real and personal.

Duncan bribes a pizza delivery girl to bring pizzas to the party, but she is chased and murdered by the same killer. The mounting casualties inside the house magnify the sense of confinement and fear. The killer continues to operate with chilling efficiency.

Upstairs, Juliette and Ken begin to have sex, but Ken is too drunk to perform, so he relies on his intoxicated impulses. He leaves and Juliette is electrocuted in the bathtub by an unseen assailant. Maria later finds Juliette's corpse in a closet, revealing the depth of the killings.

Ken heads to a lumberyard to fetch weapons, returning to the house with lethal intent. He kills Tom with a sledgehammer and then slices into his legs with a chainsaw, proving his brutality. He then moves the bodies to a van on the street and reflects on his past while reviewing a newspaper clipping about his uncle's suicide.

Back at the house, Ken barges in and kills Duncan and Frank. Maria finds Tom's dead body, and she and Janine rush for the door, only to be pursued by the killer as Maria escapes. The body count climbs as the sanctuary of the home dissolves into chaos.

Janine attempts to flee through a glass door but Ken drills her in the back, killing her. The group realizes the danger is now inside the house and not just outside, heightening the fear for the remaining survivors.

Susie hides in an upstairs closet, but Ken pulls her out and knocks her unconscious. Maria clocks Ken with a lamp, and the three survivors retreat to the basement. Jackie uses a spear gun to shoot at Ken, then they run back upstairs while Susie regains consciousness and douses Ken with bleach to blind him.

Susie, Jackie, and Maria fight back and manage to knock Ken unconscious with a croquet mallet. When he awakens, he slashes Diane with a knife, but Susie pins him down long enough for Jackie to drive the drill through his chest, killing him. A photograph of Ken as a child with his uncle is found, hinting at the killer's haunted past.

Susie answers the knocking police at the door as the credits roll. The immediate horror has ended, but the survivors must face the trauma and the mystery of what drove the killer to violence. The ending leaves lingering questions about past abuse and its impact on the present carnage.