What can you do if you're a lonely mermaid, you long for friends, and the only school is on dry land? Leena's dad has warned her that humans are dangerous, but on World Book Day, when all the children are dressed up as storybook characters, Leena grabs her chance. But with her new best friend asking questions, the Head demanding to meet Leena's parents, and loud-mouthed bully Trandulah spying on her, how long can Leena keep her secret? Around thirty...