As death row inmate Matthew Poncelet (Sean Penn) nears his execution date, he calls upon Sister Helen Prejean (Susan Sarandon) to help him with one last appeal, maintaining that he is innocent of the murders of a young couple. Poncelet begins to form a bond with Prejean, and she visits both his family and the relatives of the victims, hoping to learn more about the case. As things begin to look bleak for Poncelet, Prejean does all that she can to comfort and console the hardened convict.