In the mermaid kingdom, King Caelon disguises himself as a homeless to hunt down a traitor - only to fall for Mia, a kind-hearted mermaid who works nearby. But when Mia’s fiancé cheats on her with her stepsister and humiliates her in public, Caelon can’t hold back any longer and confesses his love. When his true identity is revealed, Mia rises from the bottom to become the most beloved, respected queen.