A good-hearted deed gets Hoi Sum Kwai (Raymond Wong)--the personification of the happy ghost--into a series of mishaps. The spirit of the late female singer Tsui Poon Hsian (Maggie Cheung) blames him for sending a pregnant woman to the wrong hospital and misses her schedule for reincarnation. She determines to seek vengeance even though she is given another chance for reincarnation. Besides harassing Hoi's students, she exploits every opportunity to humiliate him. One time, the head prefect (Fennie Yuen) is possessed by Tsui to stir up a row in a night club, causing a bunch of gangsters to be imprisoned.