Jookran High School is an ordinary high school with its pressures and requirements for the students to conform and pursue the better education. However, underneath its seemingly normal struggle between discipline and the resistance of the adolescence lie the school's dark and dirty secrets, and a terrifying fury, which is unleashed with the death of Mr. Park, a teacher of room 3-3, whose nickname was an "Old fox". The fear for the unrest in the school forces teaches to impose a "silent regime" on students who had seen the dead body of the Old fox hanging in the school's overpass. As if it had been expected, painting the scene of death by a senior classmate Ji-oh arouses a lot of abuse from a room 3-3's new teacher called Mad dog. Amid the strange rumors that spread throughout the school, Jung-sook, who always used to be compared with the Mad dog's favorite student So-young, commits suicide, and the Mad dog himself disappears with no traces left. Meanwhile, a former senior student from room 3-3, Eun-young who a literature teacher appointed to his alma mater is molested by the words left over his telephone by the Old fox the night before he died. Eun-young finally suspects that the horrific events happened in the school, had something to do with the death of her best friend nine years ago...