Bee Duofen (played by Johnnie To) and Qiu (played by Ng Man-tat) are good friends and a pair of funny plainclothes partners. They often make trouble in the police station, and even their boss Chen Ban (played by Chan Yan-kin) has a headache. However, since Qiu and Anna (played by Deanie Ip) got married, Bee Duofen has become lonely and pitiful. In the end, Bee Duofen moved to Qiu's house and formed a world of three people with a lot of jokes with the young couple. Chen Ban was so annoyed that he transferred the two to the command of Superintendent Tian (played by Tian Jun), who was known as "Shark Tian". The two were well-treated and miserable. On the other hand, Chen Ban was framed by his old enemy Flying Bandit (played by Lam Ching-ying) while performing his mission. Bee Duofen and Qiu knew that their old boss was wronged, so they made secret investigations and vowed to find out the real culprit behind the scenes...