Ricky Lau Koon-wai and Phillip Chan Yan-kin direct this supernatural crime comedy starring Sammo Hung. Tuba (Hung) is a timid cop who would rather play in the brass section of the police band than patrol the streets. One day, he becomes involved in an extortion case with trigger-happy detective Rambo Chow (David Chiang Da-wei). When Rambo is killed, he makes a half-hearted promise to avenge his death. Tuba is taken aback when Rambo's spirit appears to ensure that the timid cop follows through on his promise. Tuba eventually summons the courage to track down the baddies, aided by his hotshot partner Cheung (Jacky Cheung Hok-yau).