After graduating from the PTS police academy, Li Pak-kiu (played by Sammul Chan) and Chung Lip-man (played by Ron Ng) were assigned to patrol the Yau Ma Tei District. Pak-kiu follows the rules, while Lip-man is enthusiastic and impulsive. After reflection, Lip-man decided to support Ah-hua (played by Tavia Yeung) to study design in Japan. During a routine inspection, Pak-kiu offended a group of gangsters led by Cheung King-fung (played by Tony Leung) and Sha Qiang, and was complained about. "God of Killing" Yuan Hui-ni (played by Sonija Kwok) conducted an internal interrogation on him. One night, Ai-lin (played by Fiona Sit) and Lip-man discovered that Jing-feng and Sha Qiang were conducting illegal transactions. In order to help Pak-kiu, Ai-lin asked Lip-man to follow, but she eventually sacrificed herself to save Pak-kiu. This was a big blow to Pak-kiu, who criticized Lip-man, and the two secretly harbored grudges. However, Jing-feng was promoted to the superior of Pak-kiu and Lip-man because of his meritorious service in solving undercover cases. However, his style of doing things often embarrassed the two and caused many contradictions. Among them, Jingfeng's sister Nian'en (played by Joey Yung), his ex-wife Hui Ni, his brother Jiafu (played by Kenny Kwan) and Liwen's cousin Wenjing (played by Kate Tsui) are also involved...