After graduating from university, Michael (Andy Lau) was determined to join the police force to fight against violence and maintain public order. He was admitted into the police academy where he excelled under the rigorous training of Inspector Lau (Simon Yam). Given the increasing prevalence of drug trafficking activities, Inspector Lau assigned Michael as an undercover officer. Michael infiltrated a nightclub and became a trusted aide to the drug lord, Lu Yifan (Ronald Cheng), all while gathering evidence against him.
Michael's mother, Jiang Xia (Deannie Ip), father Qi Gan (Lau Kong), and girlfriend Wang Jiaqi (Carmen Lee) were unaware of his true intentions and mistakenly believed that he had fallen into corruption, which made them very heartbroken. Michael endured the pressure from his family while focusing on collecting evidence. After much hardship, he finally succeeded in bringing Lu Yifan to justice.