Ng and Shum had been two of the original quintet of Lucky Stars in the film Winners and Sinners and their co-stars in that film, Hung, Charlie Chin and Stanley Fung make cameo appearances in Pom Pom as their characters from My Lucky Stars, released in the following year.

Ah Chau (Richard Ng) and Beethoven (John Shum) are a pair of cops investigating a drug lord, but their ineptitude threatens to derail the case.

The police are well aware that Mr Sha (Chan Lung) is the boss of the crime syndicate smuggling and trafficking in drugs, and that he keeps details of his criminal transactions in a book which is kept by his mistress.

When Beethoven and Ah Chau investigate, they find Sha's mistress dead, and inadvertently compromise all fingerprint evidence in the hideout.

Luckily, they are assisted by beautiful cop Inspector Anna (Deannie Yip), who is secretly attracted to Ah Chau.