There’s a strange new guest at the Mermaid Hotel — a very old lady with a growly voice, bags stuffed with jewelry and coins and curiosities and a beady-eyed pet tortoise. Mabel, whose parents run the hotel, is suspicious. Who is this mysterious “Madame Badobedah” who has come to stay indefinitely and never has any visitors? Mabel sets out to prove that an eccentric new hotel guest is really a supervillain in this witty storybook about an intergenerational friendship, and Mabel realizes that first impressions can be sometimes very wrong.