Twenty years ago, a terrible dean and music teacher named Ruan Shiyin came to Hong Kong Nalan Mudd Memorial Middle School. She has formulated very strict school rules. Whenever a student violates the school rules, she will be called to the school office. No one knows what kind of punishment they will receive. Later, Fang Ping, who was also a music teacher, discovered that Ruan Shiyin was having an affair with her husband He Jintai (Nalan Mude's former principal). In anger, while Ruan Shiyin was not tired, he burned him to death in the school office. But Ruan Shiyin's body was not found afterwards. Principal He later hanged himself, and Fang Ping was also in a coma in the hospital for twenty years due to the fire...

After Ruan Shiyin's death, as long as a student violated her Anyone who established school rules would be called to the non-existent school office. They either disappeared or died in the toilet. Therefore, the school changed the school to a girls' school so that students would not have the opportunity to violate the first rule of the school rules: "It is strictly forbidden to fall in love within the school." Twenty years later, the school admitted four more boys. Terrorist incidents followed one after another. First of all, Di Zhiheng broke school rules and did not return to the dormitory at 11 o'clock. Ruan Shiyin called him to the school affairs office and died mysteriously. Secondly, Li Xisi went to the school office because the skirt of her school uniform was too short, had her legs amputated, and used her own blood to copy the school rules. Later, Li Guozhong and A Qi fell in love, and both were punished. Li Guozhong hanged himself and got the same position as Principal He. A Qi was pushed off the rooftop by Ruan Shiyin and fell to her death. In order to save other students and get rid of Ruan Shiyin, Gao Hanqiang, He Yimin, Liu Zhuobin, and Luo Shaofang entered the school after eleven o'clock, preparing to burn down the old school office. As a result, both Liu Zhuobin and Luo Shaofang were killed. With the help of Fang Ping and Teacher Fang, the location of the old school office was burned down. Gao Hanqiang and He Yimin were saved. But the ending of the story is very suspenseful. He Yimin sat in Ruan Shiyin's seat and announced Gao Hanqiang's death sentence. Some people say that He Yimin died and was the reincarnation of Ruan Shiyin, while others say that Ruan Shiyin did not disappear into ashes but possessed the body of He Yimin who was killed by him...