As a child, Deok-Su loses his father and youngest sister while escaping from a war-torn North Korea. Left only with the ripped sleeve of his sister's dress, he has little hope to ever see his family reunited again. When Deok-Su and his remaining family members arrive in the southern port city of Busan, they are taken in by their aunt, the owner of a small shop inside the bustling Gukje Market. While he, his mother, and his younger siblings struggle to eke out a living as war refugees, Deok-Su never forgets the weighty promise he made to his father--to always protect this family.