In 1962, during a period of economic difficulty in mainland China, a young man from Shantou named Ng Kwok-ho (played by Raymond Lam), fled to Hong Kong with a wave of refugees. Unwilling to be bullied by the triads, he sought refuge under the wing of triad boss Fat Po (played by Tony Cheng). After several bloody battles, Ho earned Fat Po's trust and established his position within the triad. However, as Ho's power grew, Fat Po began to feel threatened and set up a trap for Ho to be hunted down by drug lords. Although Ho narrowly escaped, his leg was permanently disabled. To avenge himself, Ho devised a honey trap, falsely accusing Po of hiding drugs, and spread the news through the media. As a result, Po was imprisoned. Ho then gained the favor of the Chief Chinese Detective by assisting him in a power struggle, which allowed Ho to take over all of Po's territories and become one of the four major families in the triad world. Ho helped those in the police force who were willing to serve him buy their way into higher ranks, turning the police station into a protective umbrella for his drug trafficking operations.
In 1973, when the Independent Commission Against Corruption was established in Hong Kong, the police force was thrown into panic. The Chief Chinese Detective advised Ho to quit his criminal activities, but due to his high rank and arrogance, Ho ended up alienating everyone, even being betrayed by his own subordinates, resulting in a thirty-year prison sentence.
This film is based on the real-life story of Wu Chung-ho, a famous large-scale drug lord in Hong Kong during the 1970s. Wu sold drugs worth over HK$300 million, involving more than sixteen tons of drugs, making him the number one figure in Hong Kong's drug trafficking organizations at the time. He was arrested on the evening of November 11, 1974, and was still in prison while this film was being shot. This case was one of the largest criminal cases in Hong Kong and was widely known among the public.