Diana and her little brother, Georgie, know every inch of the land around the old Willis place, a crumbling mansion that some people say is haunted. They climb the trees and swim in the pond. And they can do whatever they want, even stay up all night. They don't have to change their clothes, brush their hair, or go to school. They have total freedom - as long as they don't leave the grounds. When Lissa arrives with her father, the new caretaker of the estate, Diana is overjoyed. She's been wishing for a friend. She can show Lissa all her favourite spots, and they can share their favourite books. Maybe Lissa can even help her uncover the ghastly secret of the creepy old Willis house. But there are rules that must be followed in order to keep the peace. Diana and Georgie aren't allowed to make friends.