In August 1950, waiting for UN troops to arrive, the South Korean army assembled to protect Nakdong River. Only 71 student-soldiers are left behind to guard the city of Pohang. Now they are on a mission to defend the country from North Korean troops.

The sudden death of her mother brings Myung-eun back home to Jeju island. There she meets her estranged sister Myung-ju and Myung-ju's daughter Seung-ah, still living at their old home, and Hyun-ah who has lived with them for over 20 years like a relative. A career woman whose hard exterior masks her illegitimacy and abandonment issues, Myung-eun tells Hyun-ah she wants to start looking for her father after the funeral. Single-minded in her desire to dig up memories of her father and discover why he left, Myung-eun resents that Myung-ju, who like their mother is a carefree fish trader and an unmarried mother of a young daughter, seemingly doesn't care. At first Myung-ju is reluctant to accompany Myung-eun, but after Hyun-ah persuades her, guilt and her sense of duty as an older sibling prevails. And so the two sisters who are dissimilar in character...