After ten years behind the bars in Taiwan, Kong Sai-Hao (Michael Miu) finally returns to Hong Kong. Other than the hope to find his daughter Yau-Yau (Elanne Kong) to mend their relationship, he also plans for revenge. On one hand, he pretends to surrender to triad boss To Yik-Tin (Lam Lee), the man who caused him to be jailed. On the other hand, he tries to gain trust from police officers Chung Lap-Man (Ron Ng) and Lee Pak-Kiu (Sammul Chan). Lee refuses to have a criminal as his friend, but Chung becomes close to Kong to gain inside information about To's activities. Laughing (Michael Tse) doesn't trust Kong at first, but Kong uses To's wife Ching Yeuk-Sam (Kathy Chow) in the organization as an influence to help him rise up the ranks. To is killed and Kong ascends to become the head of the triad. Later, Chung becomes an official undercover agent for the police force with the intention of exposing Kong's triad crimes. He isolates himself from Lee in order to protect his undercover identity. He meets Kong's duaghter Kong Yau Yau, and Yau Yau starts to fall in love with him. Chung uses this to his advantage, gaining trust and higher rank in the triad. Later on, Kong falls deeply in love with Sum and vice versa causing him to be distracted with his drug business. Kong eventually trusts Chung and almost hands parts of his drug business to Chung to take care of. But just when Kong thought that he was in control, his drug business fails. Kong discovers that the people he trusted the most had betrayed him, including Laughing. He also misinterprets that Sum betrayed him, so he kills her. His daughter Kong Yau Yau finds out and hates him for killing Sum, whom she thought of as a mother. Chung and Lee find out that Laughing was actually also an undercover cop, and both are wracked with feelings of guilt and gain a renewed sense of responsibility to take down Kong. In the end, Kong's paranoia of betrayal causes him to be immobile for the rest of his life.