Mary Downing Hahn, author of spine-chilling ghost stories, spooky mysteries, and other books for children and teens, is a former children's librarian. She has been writing children's books for over thirty years. Her books have sold more than 2 million copies and consistently win state children's choice awards. Mary's work spans a variety of genres—historical fiction, contemporary fiction, and fantasy—but she is best known for her ghost stories and mysteries.