Charlie Decker, a Placerville high school senior, is called to a meeting with his principal over a previous incident when he struck his chemistry teacher with a pipe wrench. For unknown reasons Charlie insults his principal thus resulting in his expulsion. Furious, he sets contents of his locker on fire and collects a pistol and promptly takes his class hostage by murdering his teacher, Mrs. Underwood. Another teacher is killed shortly after. The fire triggers an alarm, but Charlie forces the class to stay put and the police department and the media arrives and this goes on over the span of four hours.
Over the following four hours, Charlie toys with various authority figures who attempt to negotiate with him, including the principal, the school psychologist, and the local police chief. Charlie gives them certain commands, threatening to kill students if they do not comply thus creating a pseudo psycho therapy group causing his schoolmates to semi-voluntarily tell embarrassing secrets regarding themselves and each other. Interspersed throughout are narrative flashbacks to Charlie's troubled childhood, particularly his tumultuous relationship with his abusive father. Several notable incidents include a violent disagreement between two female students, and a SWAT team sniper shooting Charlie in the chest. However, Charlie survives due to the bullet striking his locker's padlock, which he had earlier placed in his shirt pocket. After attempted suicide by a cop he is found not guilty of his crimes by reason of insanity.