More than 20 years ago, Meng Zhong (Huang Xiaoming), a law college student who failed the bar exam three times, was filled with despair. On a dark rainy night, he vented his long-suppressed depression and anger on a drunk passenger. As time goes by, Meng Zhong has become a well-known public interest lawyer. During an investigation of a girl's indecency case, a girl named Wei Xian (Wang Yinglu) awakened his memory of that rainy night. Behind all this, he seemed to keep hearing the echo of that nightmare: I know your secret... The film is adapted from a true story.