Mi-ja and Young-sook, two girls living on the Korean island of Jeju during a period of Japanese colonialism in the 1930s and '40s, are best friends from different backgrounds. Mi-ja is the daughter of a Japanese collaborator. Young-sook was born into a long line of haenyeo and will inherit her mother's position leading the divers in their village. Little do the two friends know that forces outside their control will push their friendship to the breaking point.