Tomboy mermaid Aliona reaches her sixteen birthday. She gets newly-grown fingernails but it comes with a condition: '"The emerald you have to find, will lead you to the merboy you seek, but don't take too long, mind, for you only have a week." On her quest, Aliona meets three unsuitable mermen, comes to realise what she'd realise what she'd like in her boyfriend and what she wants to do with her life. Then she meets Dalton helping to rescue a distressed sea turtle, follows him to the sea rescue centre, where she is offered a job as an assistant there.