The film tells the story of Hong Kong police and gangsters colluding with each other in 1973 under the instructions of the British to embezzle huge profits and harm the citizens. The Governor of Hong Kong established the Independent Commission Against Corruption. The first two prosecutors were the Black and White Evils (played by Louis Koo and Lam Ka Tung). They went through untold hardships to investigate the powerful Chief Chinese Inspector Tsui Lok (played by Francis Ng) and Po Ho (played by Tony Leung Ka Fai), and finally brought them to justice.