The play tells the story of how the police dealt a heavy blow to the "Northwest Wolf" criminal group five years ago, but the leader Gu Mulan, the backbone Lao Qiang and the undercover Lin Ke sent by the police all disappeared, and their lives and deaths are uncertain. Five years later, the "Northwest Wolf" group revived and reappeared in the arena. In order to find his mother Lin Ke (Liu Weiwei), the police officer Chu Yihan (played by Wang Ziqi) took the initiative to become an undercover agent and infiltrate the criminal group. With the support of Cheng Fan, the former deputy captain of the criminal investigation detachment and the main executor of the Northwest Wolf case that year, he went deep into the core of the criminal group step by step. In this process, Chu Yihan and Gu Linna (played by Su Xiaotong) intersected and developed a good impression of each other. The two experienced a series of conspiracies together, and finally cleared the fog in the midst of danger.