Ben is bored beyond belief after he is made to stay at his grandma's house. All she wants to do is to play Scabble, and eat cabbage soup. But there are two things Ben doesn't know about his grandma. She was once an international jewel thief, and all her life, she has been plotting to steal the crown jewels. And now she needs Ben's help ...
Who could be burgling the village's jewels? There is a gang of thieves using Peterswood as their headquarters! Luckily, Fatty's disguises are better than ever - no one recognises him as a balloon seller or the old man in the village. He is just the person to get the Five Find-Outers to the bottom of this mystery .
The theatre safe has been robbed and Boysie, the pantomime cat, is top of the list of suspects. But could his best friend and fellow actress, Zoe, be the real thief?
Thirteen-year-olds Madeleine, Theo, and Lulu, fourteen-year-old Garrison, and ten-year-old new "contestant" Hyacinth, must face their phobias and join forces to learn who is stealing wigs and pageant trophies from the School of Fear.