The Five Find-Outers and Dog, also known as The Five Find-Outers, is a series of children's mystery books written by Enid Blyton and first published between 1943 and 1961.
Set in the fictitious village of Peterswood based on Bourne End, close to Marlow, Buckinghamshire, the children Larry (Laurence Daykin), Fatty (Frederick Trotteville), Pip (Philip Hilton), Daisy (Margaret Daykin), Bets (Elizabeth Hilton) and Buster, Fatty's dog, encounter a mystery almost every school holiday, always solving the puzzle before Mr Goon, the unpleasant village policeman, much to his annoyance.
This is book 4 in the series
The Five Find-Outers are shocked when someone starts sending anonymous spiteful letters to several people in their village of Peterswood. Pip and Bets are involved when their young maid Gladys receives one of the letters, which reveals a secret - her parents are in prison for theft and she has lived in a girls home. Frightened and distraught, Gladys leaves her job. The children decide that they must discover who is sending the letters.