"If the life that you had regained, was one that I had breathed back into you... Is it too much to hope for you to love me back with that life?"

The year is 1926, in Japan-occupied Joseon. 17-year-old Soo-a is an illiterate handmaiden working for the household of a prominent Japanese collaborator. One day, she discovered an injured young man lying unconscious at the beach, an independence activist called Eui-hyeon. The sweet and innocent Soo-a nursed him back to health, and Eui-hyeon told her the tale of the "Little Mermaid," a princess of the sea who saved a prince from his death. Having fallen in love with Eui-hyeon, Soo-a was determined to meet him once again. But she knew not then, of the fate that awaited the "Little Mermaid" on her quest to reunite with her beloved.