Li Hao is a policeman. Li Hao used to be a policeman, but because of a mission mistake, Li Hao was forced to leave the police force and go undercover. In order to make up for his mistakes, he is determined to go deep into the gang to find evidence and completely destroy the gang. Li Hao hid his identity and got into the gang, and started a long and dangerous undercover career. The novel The Past of the Northeast Mafia tells the development of the Northeast Mafia in the 20 years after 1986, showing a real and morbid world of the Northeast Mafia. The novel has been adapted into the online drama "20 Years of Northeast Mafia", and there are other novels related to the past in Northeast China, such as "The Past in Northeast China". Twenty Years in the Past in Northeast China is an action crime film written and directed by Kong Ergou and starring Yu Xia, Zhang Jingchu, Hu Jun, wuyue and Zhang Xinyi. It was released in China in March, 20021.