In the police world, the open and secret struggles between different police stations are never uncommon, and the confrontation between Mapo Police Station and Seodaemun Police Station is well known. Huang Zaicheng (Park Joong-hoon) is the chief of the Mapo Police Station and a thorough actionist. Although he has not received systematic training and education, Huang Zaicheng has climbed up the career ladder with his daring and daring, and has won the recognition of his colleagues and superiors with his real achievements, but his overly rough way of handling cases has also offended many of his peers. Zheng Yican (Lee Sun-kyun) is a rookie detective who has just arrived. Zheng Yican is full of energy and ambition for his future career path and hopes to make a big splash in the workplace. The occurrence of a rape case attracted the attention of Huang Zaicheng and Zheng Yican at the same time. Both of them hope to solve the case and become the veritable "arrest king".