Five years ago, the "Northwest Wolves" crime syndicate was annihilated by the police, but the leader of the group, Gumulan, the backbone of the old gun and the undercover agents sent by the police, such as Lin Ke, all disappeared, and it is hard to know whether they are alive or dead. Five years later, the "Northwest Wolf" group resurfaced, police Chu Yihan in order to find his mother Lin Ke, took the initiative to become an undercover once again infiltrated into the crime syndicate, in the former deputy chief of the Criminal Investigation Department, the year of the Northwest Wolf case of the main executor of the support of Cheng Fan step by step in-depth the core of the crime syndicate.