Yan Jin, a businessman who used to work as a policeman, decides to investigate a drug-trafficking case that caused the death of his close friend many years ago. He decides to infiltrate into the organization as an undercover cop, and in the process gets to know Ji Xiao'ou. This causes Zhan Yu Meng, who has a one-sided crush on him, to be jealous. However, later on, Zhan Yu Meng was murdered and Yan Jin becomes the number one suspect. With Ji Xiao'ou's help, Yan Jin sets out to clear his name and to investigate the murder of his close friend.