Arlene Fleet, having made promises to God in exchange for allowing her to get away with the murder of her school's abusive high school quarterback, realizes all bets are off when the arrival of an old classmate on her Chicago doorstep ten years later draws her back to Possett, Alabama, to face her past, and to introduce her bigoted family to her African-American boyfriend.

Pathologist Dr. Maura Isles discovers that the lifeless body on the medical examiner's table is her identical twin and sets out to investigate the murder of the sister she never knew she had.