Jing Wong takes over from Gordon Chan to direct the finale of the Fight Back to School trilogy. He doesn't make much of an effort to respect Chan's earlier films though, this is a vintage Jing Wong comedy where he relies solely on the strengths of Stephen Chow to make the film work.
Chow isn't a student anymore, instead he's a police officer who has to go undercover to investigate the murder on Wong, a wealthy man. Chow is chosen because of his uncanny likeness to Wong, but when Wong's wife begins to suspect her husband might be someone else, things get very complicated for Chow.
The plot is pretty bland and people who liked the first two films should really get their expectations straight, but if you like Wong or Chow's comedy than this is a pretty decent film. There are some solid jokes, a good performance by Anthony Wong and the pacing is perfect. Silly, but entertaining.