12-year-old Seon-yu and her mother struggle for a new start after her father killed himself with huge debt behind. In the new school Seon-yu gains her smile back thanks to her reckless but innocent classmate Jung-gook. However Seon-yu's grandmother abruptly appears in the school claiming a share on the dead son's insurance money. Now Seon-yu's secret is revealed before everyone. In the meantime, Seon-yu's mother slowly loses her will to live and proposes Seon-yu a suspicious journey...