Black Snake Moan is a story set in rural Tennessee, where Lazarus, a former blues musician who survives by truck farming, discovers a young girl near his home who has been severely beaten. She is Rae, the town tramp, who has endured a life of sexual abuse from her father and verbal abuse from her mother.
Lazarus, who is also dealing with personal struggles due to the dissolution of his marriage, takes it upon himself to nurse Rae back to health. He offers her fatherly advice and teaches her about blues music, providing her with a sense of guidance and support.
Rae's boyfriend, Ronnie, misunderstands the relationship between Lazarus and Rae, and is driven by anger to seek revenge. However, Lazarus, with his understanding of violence and its motives, sees through Ronnie's intentions and becomes a mentor to the troubled young couple, helping them find a path to redemption.