It's Easter and ,once more, the Five Find-Outers- Fatty, Larry, Daisy, pip and Bets-are in a very peculiar situation they are trying to solve the mystery of the spiteful letters that arrive, unsigned, for various residents of peterwood, Mr Goon, the policeman, is also trying to unravel the mystery and comes up against Fatty who, in various disquises, manages to totally confuse him!