Karl’s life changes when he meets Frank Wheatley (Lucas Black), a lonely, intelligent boy who reminds Karl of his own isolated childhood. Frank is struggling with the recent suicide of his father and the abusive presence of his mother Linda’s (Natalie Canerday) boyfriend, Doyle Hargraves (Dwight Yoakam). Doyle is a loud, bigoted, and violently alcoholic man who terrorizes Linda, Frank, and their simple-minded friend, Charles Bushman (Jim Jarmusch).
The film opens in the present day (1996) at the Arkansas State Hospital for the mentally ill. Karl Childers (Billy Bob Thornton) is being released after 25 years of incarceration for the brutal murder of his mother and her lover when he was 12 years old. In a series of calm, measured interviews with a psychiatrist, Karl reveals his simple, rigid moral code, shaped by his abusive, religious-fanatic father and his discovery of a "sling blade" (a brush axe or kaiser blade). Sling Blade
Karl, initially an outsider, becomes a quiet protector for Frank. He spends time with the boy, sharing his love for reading (specifically the Bible and The Best of the National Geographic ) and repairing small engines. He is invited into Linda and Frank’s home for dinner, where he offers a silent, stabilizing presence against Doyle’s cruelty. Linda, desperate for any positive male influence for her son, grows to trust Karl. Karl’s life changes when he meets Frank Wheatley