The Marshmallow MermaidPaperback, 1 September 2010

At Halo McNightly's school, the swimmers are disappearing from the boys' swim team. No one can figure it out, until Halo stars investigating. A deadly mermaid lives in a cave connected to the school swimming pool. Halo will have to use her special candy to turn into various underwater fauna, such as a hammerhead shark or an octopus, to defeat the hungry girl-fish!