Hong Kong detectives Chau and Beethoven join forces with Mr. Boo in a daring mission involving a jewelry heist and a museum caper.

The Hong Kong detectives, Chau and Beethoven, are back once more. This time, their mission is to protect a young girl from a gang boss' henchmen, who are trying to eliminate her so she couldn't testify in court against their boss. Meanwhile, the plot thickens when a police medical report revealed that Chau apparently has cancer; therefore, Beethoven will see to it that his partner will have a well-deserved vacation in his remaining months.