Lee Kei (Gallen Lo) is a righteous cop who refuses to follow the majority of most Hong Kong police officers who accepted bribes during the 1960s. Wanting to move away from his supervisor who is a corrupted cop, Kei reports it to his precinct Lieutenant, who is unable to do anything about it since his superior is also corrupted. In order to protect Kei, he has him go undercover to find the infamous cat burglar "Black Rose", who has escaped being captured for over twenty years.
His first clue to finding "Black Rose" leads him to a nightclub, but he gets side tracked when he sees one of his favorite singer is scheduled to perform there. However, when Kei finds out the singer will be a no show he leaves. Walking past the back alley a man crash lands on him. The man turns out to be Tse Sei (Gordon Lam), the slick talent manager of the nightclub who is trying to escape from triads because he did not pay the talent their fees, they refuse to perform which causes the triad boss who sold the tickets to lose money. Sei and Kei are former classmates. Sei seeing that Kei resembles the singer scheduled to perform tricks him onto stage. The two almost gets away with tricking the crowds until Kei drops his sunglasses.
Kei, who is always willing help others offers to take in Sei, seeing that he can't return to his home. However Sei soon worn outs his welcome when he ask to borrow Kei's clothes and accessories to wear. The next day Kei finds out his corrupted supervisor knows about his undercover assignment. His corrupted supervisor tells Kei that if he is unable to solve his undercover assignment in one month he will use it as an excuse to fire him. Life for Kei gets worse later that day when he is returning home. He finds out that the triads that are looking for Sei have burned down his home.
To make it up to Kei, Sei brings him to his uncle's home to live. Sei's uncle works at an amusement park and live together with all the employees in the same apartment. At the amusement park Sei gets re-acquainted with all his former neighbors which includes brassy girl Siu Fong-fong (Elaine Ng), who tends the coin toss game booth at the park. After dinner Sei brings Kei around the amusement park to see other attractions. At one of the attractions Kei is automatically volunteered to be an assistant at a martial arts attraction. After being scare out of his wits he recognizes the martial arts used by the performers is similar to those used by "Black Rose". Kei decides to stay close to the performer Cheng Po-chu (Maggie Cheung Ho-yee) and her mentor who he suspects is the infamous "Black Rose".