12-year-old Hyuk lived with his mother and younger siblings, Seon-ah and Jun, until a torrential rainstorm caused a reservoir to collapse one night, leaving his mother missing. Left as orphans, the three siblings set out to find their father in Dongjak-dong, Seoul. Upon learning that their father died in the Vietnam War and is buried there, the siblings, after wandering, receive help from a righteous old man named "Mr. Lee" to settle in Seoul. When Mr. Lee dies in an unexpected accident, the three siblings, driven by the conviction to find their mother and a spirit of self-reliance, work and study diligently. After much effort, they finally find their mother, but she has lost her memory due to the shock of saving her children during the flood and has since started a new family with another man. As their mother fails to recognize them, Hyuk’s persistent efforts and the cooperation of her husband help her recover her lost past and return to normal, leading to a tearful reunion where the three siblings embrace their mother.