C.L.I.F. 4 picks up where the previous season leaves off with the CID team launching a crackdown on the criminal gang that Yang Zhongzheng (Terence Cao) belongs to. There is a new bad guy in town, collaborations with the Taiwanese Interpol, and more exciting and complicated cases to crack in this series as the police officers fight crime and evil to uphold law and justice. Zhang Guixiang (Elvin Ng), who played a traffic police officer last season, will return to his NPC Community Policing Unit (CPU) as Senior Staff Sergeant and will take his relationship with Weng Xuanmei (Sora Ma) one step further as marriage is on the cards for the couple. The other anchor couple, Wei Lantian (Li Nanxing) and Huang Zhijie (Rui En) will welcome a new member to their family but that doesn’t mean Zhijie will sit out of all the crime-busting action as the pair will continue to head their respective teams in the Criminal Investigation Department (CID). New characters include Chen Yu (Zhang Yaodong), Wang Shishi (Ya Hui), Cai Yanqi (Mei Xin), Zhou Jingze (Yusuke Fukuchi) and Zhao Xuewei (Chen Tianwen). Out of the 5 new characters, 4 of them are among the 8 main characters of this series. Chen Yu, a spot-on police officer, is stuck in a love triangle between Wang Shishi and Cai Yanqi, who are both police officers (Yanqi joined later). Yanqi was once his ex-girlfriend who still had feelings for him. At the same time, Chen Yu isn’t on good terms with his superior officer, Huang Zhijie.
