Fifteen year old boy is facing justice for robbery. In an attempt to reduce his sentence his family offers the judge, An Hui, a large sum of money through his lawyer. The funds are instead embezzled by his lawyer, and the boy is sentenced to jail for three years. He is embittered when his mother dies while he is in prison, and he vows to find evidence of An Hui accepting the bribe, and hopes thereby to send her to prison.

Released from prison, the boy ends up at her doorstep with his own ulterior motive, and soon has established himself as a guest in her household. While in An Hui’s trust he steadily carries out his plan of discovery, taking notes and planting bugging devices about her home. He finds nothing, but is instead affected by her kindness to him and to other wards of the juvenile court.

Upon learning that his mother sold her kidney for a large sum to present to An Hui, he is consumed by hatred. He accuses her before the procurator, exposing his plan to ensnare her. Despite the betrayal by her houseguest, An Hui calmly protests her innocence, satisfied that the boy has resorted to legal redress.

He leaves her house, but is detained as a vagrant. An Hui later has him released.

While celebrating his 18^th birthday, a long forgotten letter appears, revealing the true facts exonerating An Hui. Till now, as a man, he sees clearly that An Hui has played the part of his true parent.