Petronella isn't a typical witch: she is kind and cheerful, and lives in a magic house in an apple tree near an old abandoned mill. One day a new family moves into the mill, and Petronella doesn't know what to expect from her new neighbors. When Luis and Lina, the children of the family, come to visit Petronella she realizes they can be friends. Which is just in time for her to help the children win an important contest.