American twins Bud and Lindy move to England when their father's transferred there. When their English grandmother becomes ill, the twins stay with their Aunt Edythe and Uncle Clifford. Uncle Clifford writes and illustrates a series of children's books about the little people called the Turnipins. Much to the children's surprise, they find in the woods a small door attached to a tree fronting a hill. Inside they discover that the Turnipins are real! - even if they can only appear in their real guise to children.
When the wee home of the Turnipins, Jessica and Cyril Cairnbracken, is threatened by developers, Bud and Lindy promise to find a way to help. But the magical Token they're given by the Turnipins, while it does what it was intended to, has some unpleasant and unforeseen results!