A phone call reaches the home of Kim Eok-man (Jung Min), Korea's largest conglomerate, looking for his second wife, Lee Soon-hee (Kim Ji-mi). The caller is her ex-boyfriend, Go Geun-tae. He threatens to reveal Soon-hee's past to her husband and demands money. Soon-hee had a brother named Yeong-sik, who frequented the underworld. When Yeong-sik was being chased by Go Geun-tae, a member of a violent organization, Soon-hee had to cohabit with Geun-tae in exchange for her brother's life. However, Yeong-sik was eventually killed by him. She fled from Geun-tae, attempted suicide, but was narrowly rescued and began a new life before meeting Eok-man. Seong-jin (Kim Jeong-cheol), Eok-man's only son, sensing his stepmother's unusual expression, began to eavesdrop on her phone calls. Having learned the entire situation, Seong-jin decides to meet Geun-tae in person to give him money and resolve the situation. As a filial son, he did not want his father, who had lived alone for a long time after his biological mother's death, to suffer further. However, Go Geun-tae continues to threaten and demand more money. Unable to procure the money, Seong-jin is brutally beaten by Geun-tae and accidentally kills him. Bloodied, Seong-jin seeks out his fiancée Go Eun-young. Together they listen to a radio broadcast, and to Seong-jin's surprise, he discovers that Geun-tae is Eun-young's brother. Seong-jin, who tried to practice filial piety but ultimately became his fiancée's enemy and caused his father suffering, leaves a letter for his father and Eun-young before surrendering. Upon learning all this, Soon-hee struggles between gratitude and guilt. Eun-young, though weeping at fate's cruelty, forgives Seong-jin, and Eok-man feels both gratitude and sorrow for his son's filial piety and misfortune. Seong-jin is imprisoned, leaving behind everyone's tears.