After a fateful night with human heir Quentin Whitmore, mermaid Isla Mourne leaves behind a mysterious pink pearl and secretly takes his jade pendant. Six years later, Isla returns to the human world with her son, Ethan Mourne, only to be betrayed by her best friend, Selene Hartley, who steals both the pearl and the pendant. Posing as Isla, Selene approaches Quentin. But when she suffers a severe allergic reaction, Quentin begins to suspect something's off. Meanwhile, Isla and Quentin keep missing each other until Ethan's unusual traits and allergies finally catch Quentin's attention. As the truth unravels, Selene's lies are exposed, Isla and Quentin are reunited and a long-lost family finally comes together.
