Hyun-sook (Kim Hee-ae) struggles to raise her two daughters, Man-ji (Go Ah-sung) and Cheon-ji (Kim Hyang-gi) on the meager income from her supermarket job. Although Man-ji and Cheon-ji are sisters, they are completely opposite to one another. Man-ji is a loner and is rebellious. Her relationship with her family members is cold. In contrast, Cheon-ji is an obedient child who always tries to make her mom happy. Unexpectedly, the optimistic child, Cheon-ji, ends her own life one day. This tragedy strikes Hyun-sook’s family, making their tough life even more difficult. Despite the death of Cheon-ji, Hyun-sook and Man-ji stay strong to put their life back together. By chance, Man-ji accidentally discovers some information about her sister. These information make Man-ji realize the underlying truth of her sister’s death and a hidden secret that can never be disclosed....