The film begins with Teapot (Sammo Hung), attempting to rob the dormant homes of a wealthy neighborhood in Hong Kong. When attempting to rob one particular house, he is briefly mistaken for the guest of honor at a surprise birthday party, and is subsequently handed over to the police. The following day, four other petty criminals are apprehended - unruly civil rights leader Curly (John Shum), car washer Exhaust Pipe (Richard Ng) who steals vehicle parts, well-dressed thief Vaseline (Charlie Chin) who swindles jewelry shops' most expensive watches, and Rookie (Stanley Fung), a mysterious, and rude, stranger. The quintet unite in prison and promise to make their fortune together in every possible way upon their release. Rookie is the gang's leader, whilst Teapot is bullied by the others (in the later films, Roundhead, played by Eric Tsang, is the group's victim and Hung's character is the leader). Following their release, they team up with Curly's beautiful sister, Shirley (Cherie Chung), and form a cleaning company.
A sixth convict, the wealthy Jack Tar (James Tien) is released on the same day. Upon his release, he returns to his mansion, his fleet of expensive vehicles and his dozens of bodyguards. Tar commences work on his next criminal project, trading counterfeit US and Hong Kong currency with another crime boss. When the deal takes place, a brave but careless cop CID 07 (Jackie Chan) attempts to recover the briefcase containing the phony money, but the case somehow ends up in the Five Stars Cleaning Co. van. While none of the workers realize this misfortune, Tar certainly does. Later, Teapot and his friends decide to attend Tar's high-class party, hoping to expand their business with the wealthy guests. Unluckily Tar recognizes Curly instantly, and interrogates him. A battle ensues, where Teapot's kung fu skills are heavily relied on. Finally, another Triad gang, led by Tar's rival, wants the printing plates as well. A climatic fight takes place at a warehouse, where both Tar and his rival, along with their goons, are finally defeated. At the end, Teapot receives a reward and marries Shirley.
