In rural Louisiana a boy and girl sit beside a lake on a date. They listen to music and kiss. The De Rocher brothers, who are hiding close by, emerge. Anthony grabs the boy while Joseph begins to rape the girl. Anthony continues to struggle with the boy before taking out a gun and shooting him in the head. The girl screams at the sound of the gunshot. In a panic, Joseph stabs her until she goes silent.
At Hope House, Sister Helen Prejean is teaching a group of children a hymn. As the children leave, she tells her Sisters that she accepted a request from an inmate to be his spiritual adviser. The Sisters warn her of the dangers, but she remains firm that this is her duty. As she drives to the state prison she muses over her decision. When Sister Helen arrives at the prison she is met by Father Grenville. He warns her that De Rocher, the prisoner with whom she will be meeting, is unreachable. She tells the priest that it is her duty to help the man. Father Grenville introduces her to the Warden, who also warns her about De Rocher. Upon meeting De Rocher, Sister Helen finds him to be easygoing and friendly. De Rocher asks Sister Helen to speak at the pardon board on his behalf. Sister Helen agrees. At the parole board hearing De Rocher’s mother and brothers plead for his release. One of the victim’s parents, hearing De Rocher’s family’s pleas, lashes out in anger. Afterward, the victim’s families confront De Rocher’s family and Sister Helen. At that moment, word comes from the pardon board that De Rocher will not be pardoned – he will die for his crime, barring intercession from the governor. When Sister Helen tells De Rocher, he becomes angry and accuses Sister Helen of abandoning him. Sister Helen says she will not abandon him, but encourages him to admit to his crime and ask forgiveness. De Rocher, however, refuses. In the waiting room, Sister Helen searches for money in her purse for the vending machine. She begins to hear the voices of her students, her Sisters and others, telling her to stop helping De Rocher. As she is listening to the voices, the warden tells her that the governor will not commute De Rocher’s death sentence. Upon hearing this, Sister Helen faints.
A guard enters De Rocher’s cell to tell him that his execution date has been set. As the guard leaves, Joseph muses on his fate. Back at Hope House, Sister Helen wakes up from a nightmare. Sister Rose begs her to stop working with De Rocher, saying it can’t be good for her health. But Sister Helen says she cannot, as it is her duty. On the evening of De Rocher’s execution, Sister Helen and De Rocher are talking in his cell, discussing their mutual love for Elvis. Before leaving, Sister Helen urges De Rocher to confess and ask forgiveness, but he refuses. Mrs. De Rocher and her two other sons enter. De Rocher attempts to apologize to his mother. Mrs. De Rocher will not accept, choosing to believe that her son is innocent. As De Rocher is led away, Mrs. De Rocher breaks down and Sister Helen comforts her. Outside the execution chamber, Sister Helen meets with the victim’s parents. They ask if she is bringing them an apology from De Rocher. When Sister Helen says she does not have one, they again lash out in anger. The girl’s father takes Sister Helen aside and says he is not sure that he wants De Rocher to die and that the stress has damaged his marriage. Sister Helen consoles him. With De Rocher’s impending execution, he and Sister Helen talk one last time. Sister Helen once more urges him to confess. He finally breaks down and confesses. Sister Helen forgives him and says that he must look at her during the execution and she will be his source of comfort. The warden comes to escort De Rocher to the execution chamber. The warden asks if De Rocher has any last words. Joseph asks for forgiveness from the parents of the murdered teenagers. The warden then gives the nod for the execution to proceed. As De Rocher dies, he tells Sister Helen that he loves her.