The Janjilons are not what they seem. They look like a type of monkey but they are really children. How did they turn into Janjilons? And could it happen to anyone?

Behind this mystery is someone evil, Judge Ormerod who wants to be the next Duke of Westshire. With the help of three weird sisters, he has to rid the land of clever children from being an obstacle to him. The Janjilons work for him as the three sisters mete out punishment and keep them locked up.

Petronella starts to look into these strange happenings. But time is running out because when the Judge no longer needs the Janjilons, they will be destroyed.