The movie is shot as a documentary set in a world where the supernatural killers depicted in famous slasher films are real. A female journalist named Taylor Gentry and her two cameramen document the preparations of Leslie Vernon as he prepares to join the ranks of other slasher villains. Leslie takes his identity from an urban legend about a boy who killed his family and was cast into a river by angry townsfolk. He initially claims to be the vengeful spirit of the slain boy, but soon admits that he is an ordinary man named Leslie Mancuso who must rely on conventional tactics rather than supernatural powers, implying that the other killers in his line of work did the same.Taylor and her crew film Leslie's meticulous preparations to slaughter a number of teenagers in an abandoned house and then be confronted by a virginal "survivor girl", Kelly. Leslie plans his crime down to the smallest detail, cheerfully explaining the many tricks and "trade secrets" he utilizes to engineer what will only appear to be a spontaneous night of horror. His preparations include modifications to the house and careful manipulation of his future victims. While luring in his selected survivor girl, Leslie is overjoyed when a man named Doc Halloran arrives to serve as his nemesis; he terms him his "Ahab". Leslie also introduces the crew to his mentor, Eugene, a retired killer from the time before characters like Jason Vorhees and Freddy Krueger became popular.Taylor and her crew come to share Leslie's enthusiasm for his project, but their consciences catch up with them on the night of the murders . They beg Leslie to call off his spree, but Leslie is adamant, believing that his survivor girl will define herself by attempting to defeat him. Taylor and her crew abandon their documentary, and at this point the film shifts into a traditional presentation. Taylor attempts to warn and rally the remaining teens together to fight Leslie, but Leslie's preparations continue to give him the upper hand. The group looks to Leslie's survivor girl for leadership, but she unexpectedly dies. Taylor quickly realizes that, as a virgin herself, she was Leslie's true survivor girl all along. She faces Leslie and defeats him in the exact manner he had laid out for her, then burns down the shed in which he was defeated.However, Leslie's preparations included slathering himself with flame-retardant gel and feigning death. Over the final credits, security camera footage reveals Leslie's charred body sitting up on the autopsy table, still alive.
The next great psycho horror slasher has given a documentary crew exclusive access to his life as he plans his reign of terror over the sleepy town of Glen Echo.