This film takes place in Hong Kong, where Mainland Chinese MPS officer Cheng Shih-nan (Cheng) extradites drug-dealer Wong Ti (Chow) to the Royal Hong Kong Police. Unfortunately, Wong escapes and Cheng is forced by the State Council to stay abroad Hong Kong and assist Chief Inspector Wu Wei-kuo (Leung) to track down Wong, as well as his boss, So Kuo Jung (Fang). The cultural differences between Hong Kong and Mainland China and her rivalry with Wu's father, a former military officer of Kuomintang, become a big headache for Cheng, a loyal member of the Chinese Communist Party.