RETURN TO HORROR HIGH

In 1982, the town of Crippen was rocked by a series of murders at Crippen High School. The killer was never caught. Several years later, Cosmic Pictures, headed by sleazy producer Harry Sleerek, arrives in Crippen to make a biographical movie about the crimes titled Horror High. To maximize the production's low budget, the cast and crew temporarily move into the real Crippen High School, where they are to film on location; the lead actress, Callie Cassidy, is hired to play multiple roles. In the midst of the film shoot, multiple disappearances and murders occur, which are subsequently investigated by police Chief Deyner and Officer Tyler. While the bodies are recovered from the school, Chief Deyner and Officer Tyler interview the film's screenwriter, Arthur Lyman, outside, and he recounts the events on-set:

Some days prior, lead actor Oliver informs director Josh Forbes that he is dropping out of the production. Before leaving, he is murdered in an empty wing of the school. Harry immediately replaces Oliver with Steven Blake, a real-life police officer and former Crippen High student. Tensions on set rise when Harry insists Callie show on-screen nudity, while Arthur is forced to repeatedly make script changes to accommodate Harry's requests for more gore. One day, an extra is murdered, followed by Choo Choo, a special effects assistant. Shortly after, cast member Richard Farley is caught in a booby trap that drags his body into a steel-blade industrial fan.

While wandering the high school in-between scenes, Steve recounts to Callie his relationship with his high school girlfriend, Kathy; her father, Crippen's Principal Kastleman, is on-set serving as a technical advisor, but Steve has not seen Kathy in years. Meanwhile, Callie begins noticing that cast and crew are disappearing. Fearing the killer has returned, she and Steve begin their own private investigation. Callie's discomfort is compounded one day while watching the filming of a brutal scene in which the school biology teacher, Richard Birnbaum, is dissected.

Later, Steve notices a photo of Kathy on the set; when he inquires to Principal Kastleman about Kathy's whereabouts, he claims she is in graduate school. That night, Steve and Callie find a trail of blood in the hallway, and discover Harry and Josh's corpses, as well as a trapdoor leading to a basement. In the basement, they find a classroom full of the decomposed victims of the 1982 massacre, all posed in desks. They are confronted by Amos, the school janitor, who attacks Steve. During their fight, Steve inadvertently removes a latex mask from Amos's face, revealing him to actually be Principal Kastleman in disguise. Kastleman explains how years ago, Kathy discovered she was pregnant with Steve's child, after which Kastleman murdered her in a rage and hid her body in the school basement before killing multiple students. Callie and Steve manage to overpower Kastleman, impaling him with a javelin.

In the present, after Arthur finishes recounting the events to Chief Deney and Officer Tyler, the police enter the school to investigate. While they do so, Arthur calls out "all clear" outside, upon which all of the victims–who have been laid in the grass and covered in sheets–rise; they have in fact been alive all along. In reality, Callie and Steve uncovered in their research that Kastleman was in fact the true killer in the 1982 massacre, and killed him in the basement. Harry decided to capitalize on this by devising a mock massacre centered around the revelation as a publicity stunt to help promote the film. In the basement, police find Kastleman, still impaled by the javelin, but alive; he lunges at them, leading them to shoot him multiple times. When they return outside and find the bodies of the film crew inexplicably gone, they assume there is still a killer on the loose.

Later, Arthur sits at a typewriter to compose a new screenplay he has called Return to Horror High, which he intends as a sequel. A framed photo of Principal Kastleman sits on his desk. An unseen figure enters the room and stops at Arthur's typewriter, dripping blood on the pages being typed. Arthur looks up at the unseen figure and says, "Dad?"

Principal Kastleman is revealed to be the killer, having murdered his own daughter and others. He is exposed and overpowered by Callie and Steve, who impale him with a javelin.

The film wraps its meta approach by resolving both the on-set murders and the original high school massacre through the revelation of Principal Kastleman as the killer. By unmasking the true antagonist and having the protagonists defeat him, the story pays off its blend of horror and satire, drawing a bloody line between fiction and reality while lampooning genre conventions.