The Merriott sisters are born into a comfortable middle-class life and their house, situated on the edge of Richmond Park, is full of fun and laughter. But then Letty, the fourth girl, arrives and tensions suddenly appear in the once happy home. For unbeknownst to the sisters, much depended on the new baby being born a boy - not least the happiness of their parents' marriage. Letty has a beautiful face but a withered arm and while the girls and their mother can accept and love her as their own, her father's resentment of her is tantamount to dislike. It is only when Aunt Rosabel, their mother's great-aunt, arrives for Christmas that all their fortunes change. Within months the Merriotts find themselves living in a great house, Merrylands in Wiltshire, with the promise of everything they, but most of all their father, have ever wanted. Unfortunately, Aunt Rosabel is not what she seems and before long the family find themselves worse off than they have ever been.