Lily, 17, appears to be your average high school student, but she's got a secret: Lily is really Princess Waterlily, a mermaid and the heir to the throne of the undersea kingdom of Thalassina. Before her 18th birthday, Lily must find a mate or else lose her royal inheritance. All she has to do is kiss the boy of her choice, and they'll be bonded for life. Lily plans to bond with her crush at the upcoming Halloween party. Unfortunately, she kisses her annoying neighbor by mistake. What's a (mer)girl to do?