Five years ago, the police dealt a heavy blow to the "Northwest Wolves" criminal group, but the leader Gu Mulan, the backbone "Lao Qiang", and the undercover agent Lin Ke sent by the police all disappeared, and their lives were uncertain. Five years later, the "Northwest Wolves" group revived and reappeared in the Jianghu. Police officer Chu Yihan, in order to find his mother Lin Ke, took the initiative to become an undercover agent and infiltrated the criminal group. With the support of former deputy captain of the Criminal Investigation Brigade and the main executor of the Northwest Wolves case, Cheng Fan, he further penetrated into the core of the criminal group. During this process, Chu Yihan and Gu Linna intersected and developed a mutual affection. Together, they went through a series of conspiracies, ultimately clearing the thick fog amidst the dangers.