A timeless story celebrating friendship and imagination, from an exciting new voice in children's literature. Mabel lives with her parents in The Mermaid Hotel, by the sea. Mabel likes to keep an eye on the comings and goings of all the guests. Then one day a particularly in-ter-est-ing old lady comes to stay. There is something very suspicious about her, with her growly voice and her heavy trunks and her beady-eyed tortoise. And why does no one know her REAL name? There can only be one answer, Mabel decides ... this guest is a SUPERVILLAIN.