Sling Blade

Sling Blade is a 1996 American drama film written and directed by Billy Bob Thornton, who also stars in the lead role. Set in Arkansas (filmed in Benton, Arkansas) the film tells the story of a man named Karl Childers who has an intellectual disability and is released from a psychiatric hospital, where he has lived since killing his mother and her lover when he was 12 years old, and the friendship he develops with a young boy and his mother. In addition to Thornton, it stars Dwight Yoakam, J. T. Walsh, John Ritter, Lucas Black, Natalie Canerday, James Hampton, and Robert Duvall.
The film was adapted by Thornton from his previous one-man show entitled "Swine Before Pearls," from which he developed a screenplay for the 1994 short film "Some Folks Call It a Sling Blade", directed by George Hickenlooper. "Sling Blade" proved to be a sleeper hit, launching Thornton into stardom. It won the Academy Award for Best Writing, Adapted Screenplay, and Thornton was nominated for Best Actor in a Leading Role. The music for the soundtrack was provided by French Canadian artist/producer Daniel Lanois.
"Sling Blade" was filmed over the course of 12 days on location in Benton, Arkansas. and was produced by David L. Bushell and Brandon Rosser.
Plot.
In the mid-1990s, Karl Childers is an intellectually disabled Arkansas man who has been in the custody of the state mental hospital since the age of 12; at that age, he murdered his mother and her lover. Although thoroughly institutionalized, Karl is deemed fit to be released into the outside world. Prior to his release, he is interviewed by a local college newspaper reporter, and he recounts committing the murders with a kaiser blade, saying, "Some folks call it a sling blade. I call it a kaiser blade." Karl explains that he attended school with the teenage son of his father's boss, Jesse Dixon, who was a mean-spirited bully and pervert; he thought that Jesse was raping his mother and decapitated him. When he discovered that his mother was a willing participant in the affair, he killed her also.
Thanks to the doctor in charge of his institutionalization, Karl - who is highly skilled at repairing small engines - lands a job at a repair shop in the small town where he was born and raised. He befriends 12-year-old Frank Wheatley and shares details of his past, including the killings. Frank reveals that his father was killed when he was hit by a train. He later admits that he lied and that his father committed suicide.
Frank introduces Karl to his mother, Linda, and her gay friend, Vaughan Cunningham. Vaughan is the manager of the dollar store where Linda works. Despite Vaughan's concerns about Karl's history in the mental hospital, Linda allows him to move into her garage - which angers Linda's abusive, alcoholic boyfriend, Doyle Hargraves. Karl bonds with Linda, Vaughan, and their friends. Vaughan warns Karl about Doyle's violent demeanor as well as his fears that Doyle might hurt or kill Linda and Frank.
Karl becomes a father figure to Frank, who misses his real father and despises Doyle. As they grow closer, Karl reveals to Frank that he is haunted by an incident that happened when he was six or eight years old. His parents performed an abortion of his unwanted baby brother. The baby was wrapped in a bloody towel and given to Karl with instructions to "get rid of it"; however, Karl realized that the infant survived the abortion. He then buried him alive to spare him the abuse and neglect Karl had received at the hands of his own father. Karl later visits his father, who has become a sickly hermit. Karl tells his father that killing his baby brother was wrong and that he had wanted to kill his father for making him do it but decided that he was not worth the effort. Karl thereafter decides to be baptized.
Doyle continues his abusive behavior. Linda tries ejecting him from the house, which results in a physical confrontation. Frank is enraged and hurls household objects at Doyle until he leaves.
Linda and Doyle reconcile, and Doyle announces his plan to move into the house permanently. He claims he will soon propose marriage to Linda, says that Karl is no longer welcome to live in the house, and demands that Frank begin obeying his orders. Frank does not acquiesce and Doyle attempts to attack him, but Karl stops him and warns him never to touch Frank again. Karl begins to realize that, eventually, either Frank will kill Doyle and end up like him, or Doyle's abuse will kill Frank or Linda or both. 
In order to prevent this, Karl has Frank and Linda spend the night at Vaughan's house while he goes to Linda's house with a lawnmower blade he has fashioned into a weapon. He finds a drunken Doyle inside and kills him with two blows of the blade to the head, then phones the police to turn himself in, and requests a hearse for Doyle. 
Returned to the state hospital, he is less passive than he was during his previous institutionalization and silences a sexual predator who had previously forced him to listen to stories about his crimes, before standing to look out of a window towards an open field.
Production.
Thornton first came up with the character of Karl while working on the film The Man Who Broke 1,000 Chains. He developed the idea into a monologue which became a one man show, which he used to raise the funds to make the film.
The film was made with a production budget of $1 million financed by The Shooting Gallery, and was sold to Miramax for $10 million, which at the time was a record price for an independent film.
Reception.
The film grossed $24,444,121 in the United States against a $1 million production budget. It grossed a further $9.7 million in other territories for a worldwide total of $34 million. 
Critical response.
On Rotten Tomatoes the film has a "Certified Fresh" rating of 96% based on reviews from 56 critics, with an average rating of 8.40/10. The site's consensus states "You will see what's coming, but the masterful performances, especially Thornton's, will leave you riveted." On Metacritic it has a score of 84% based on reviews from 26 critics.
"The Washington Post" called it a "masterpiece of Southern storytelling." Kevin Thomas wrote in the "Los Angeles Times" that the film is "a mesmerizing parable of good and evil and a splendid example of Southern storytelling at its most poetic and imaginative". "The New York Times" critic Janet Maslin praised the performances but said that "it drifts gradually toward climactic events that seem convenient and contrived".