Return to Horror High is a horror comedy movie that follows a police investigation into a series of gruesome murders at a high school. The story is told in a nonlinear timeline, with a screenwriter and a film producer working on a movie about the killings. As the investigation progresses, the film crew experiences strange and terrifying events themselves. The movie combines elements of slasher films, teen slashers, and meta-horror, with plenty of gore, violence, and surprise twists.

In Horror High, a high school student named Vernon becomes the victim of a cruel science experiment, transforming him into a monstrous killer. Seeking revenge against his tormentors, Vernon goes on a killing spree within the confines of his school, targeting both students and teachers. As the body count rises, the police are called in to investigate the mysterious murders. Will they be able to stop Vernon before he claims more innocent lives?