This is about a girl named Emily Windsnap, who finds out she is half-mermaid when taking a swim class. That is the start of the story and then she meets another mermaid named Shona and then she goes to rescue her dad from prison...underwater prison that is. Thats right, her dad is a mermaid and her mom's a human and they fell in love and got married, even though it was totally illegal. This book is part adventure, part fantasy and a little part romance.