Annabel Grey has been brought up to be a very proper young lady. But when her mother suddenly leaves to go abroad, Annabel is sent to live with her aunts. They make an extraordinary claim: Annabel is from a long line of witches, and her life, until now, has been an illusion. But before Annabel can decide if she believes this ridiculous story, a terrible spell begins to spread over London, threatening to devour the city. Only a most magical girl can prevent the disaster.
