"Sins do not disappear after serving their sentences. How can sin-eaters be redeemed?" - "The Sin-Eater" Wang Xiang (Zhuang Kaixun), who was sentenced for murdering high school girl Li Xiaojun (Cai Ruixue), was finally released on parole after more than ten years in prison. Wang Xiang's return home has brought a lot of shocks to the originally peaceful lives of his mother (Ying Cailing) and his younger brother Wang Jie (Cao Yanhao). Wang Xiang originally planned to start a new life quietly, but because of a traffic accident, his past was exposed, and he unexpectedly reunited with his girlfriend Shen Wenqing (Xia Yuqiao) from college. At this time, the teenage girl he met by chance disappeared unexpectedly. The police, the girl's mother, and the family of the victim at that time all believed that he had committed a crime again... When the perpetrator identified by everyone becomes a victim with no place to refute, how can he break through social discrimination, gain the forgiveness of the victim's family, and regain his ordinary life?