In 1982, at Crippen High School, a serial killer escapes justice following a murderous rampage. Five years later, Cosmic Pictures comes to town to make a film about the Crippen High murders in the abandoned school where they occurred. However, shortly after filming begins, police are called to the scene to investigate another massacre. Officers estimate seven or eight people have been killed, but cannot be sure because the murderer dismembered the corpses and scattered the body parts. Police Chief Deyner interrogates the only survivor, Arthur Lyman, who wrote the screenplay and was a student at the school at the time of the original murders. Lyman expresses his resentment of sleazy producer Harry Sleerik, who cut costs by deferring salaries and boarding the cast and crew at the school. Arthur relates his knowledge of the murders to the chief. The first victim is Oliver, an actor who quit the production to star in a television show. As he leaves the school, Oliver is murdered by a man wearing a white mask, a black hooded robe, and yellow gloves. Police officer and technical advisor Steven Blake, a former Crippen student, replaces Oliver. He befriends lead actress, Callie Cassidy, and tells her that while he was a student, he dated a girl named Kathy Johnson, unaware that she was the daughter of the school principal. They fell in love, but she never returned after summer vacation. Amos, the school janitor, and Principal Kastleman also serve as technical advisors. Two more crewmembers are murdered and the cast fear that the killer has returned. When Steven inquires about Kathy’s whereabouts, Kastleman claims she is in graduate school. After making love in one of the classrooms, Steven and Callie discover blood in the hallway and follow it to the men’s restroom. Continuing their investigation, Steven and Callie find a number severed heads, as well as a secret passageway to the basement, which contains a room filled with human skeletons. Amos attacks Steven, and as they struggle, Steven removes the janitor’s mask, revealing him to be the principal. Kastleman accuses Steven of impregnating his daughter, who gave herself an abortion. The principal hints that he murdered Kathy, as well as the other students, and hid their bodies in the basement. He attacks Steven and Callie, and they impale him on a javelin. As Arthur finishes his story, Police Chief Deyner orders his men to the basement. Once they are gone, Lyman yells, “All clear.” The many corpses on the lawn suddenly come to life, revealing that the recent murders were part of a stunt to generate publicity for the film. Harry Sleerik confesses that he did not think the plan would work until Callie and Steven discovered that Kastleman was the real killer. Meanwhile, in the basement, Kastleman springs to life and lunges at the officers before he is felled by gunfire. When police discover the bodies missing, they assume “some sicko” took them. Arthur Lyman sits at his typewriter, and begins typing his latest screenplay Return to Horror High, which he intends as a sequel. Kastelman enters, dripping blood on the pages, and Arthur addresses him as “Dad.”