Inspector Jiang Zishan (played by Chan Kam Hung) is calm, thoughtful, and objective. Although he cooperates with the arbitrary sergeant Xu Fei (played by Louis Koo), he can still use softness to overcome hardness, make full use of the other party's keen intuition and rich experience, and repeatedly solve strange cases. With the help of Jiang Zishan, Xu Fei also made many great contributions, and his career also improved. The two people with different personalities became good partners and good friends. In life, both of them are entangled in two unsolvable relationships. Jiang Zishan and his girlfriend Wen Wanlan (played by Charmaine Sheh) have been in love for many years and have a stable relationship. However, Wen Wanlan's good friend Tang Xinru (played by Li Shanshan) fell in love with Jiang Zishan at first sight. After Wen Wanlan was imprisoned for her father's case, Jiang Zishan and Tang Xinru gradually developed, but with Wen Wanlan's release from prison, the relationship between the two began to waver. Xu Fei has never been able to forget his girlfriend Liang Qianqian (played by Heung Hoi-lam) who has been missing for many years, until he met the police psychologist Wu Qiaojun (played by Jessica Hsuan), the two sparked and prepared to get married. At this moment, Xu Fei suddenly received news from Liang Qianqian, and faced a difficult choice between his new love and his old love.