The outspoken and daring Lei Lok (Aaron Kwok) and the introverted and resourceful Nan Jiang (Tony Leung Chiu Wai) join hands by chance to break the old rules and build up their power. With the mediation of Lei Lok's wife Cai Zhen (Du Juan), they become the "two hero detectives" known to everyone in both the black and white worlds. Since then, the two have dominated Hong Kong for 30 years. However, under the surface of peace and checks and balances, fighting, murder, betrayal, power grab... undercurrents are surging and ready to explode!