At the end of this movie, it left me thinking "Was that all?"  After I got home, though, I realized that no, it was not all.  Billy Bob Thornton really brings to life this true-to-life tale of a mildly retarded man, Karl, who is placed in a mental hospital for killing his mother and her secret lover with a sling blade.  His reasons for killing them were simple to him, he wanted to help.  All he ever wanted to do was the right thing, and why was he condemned for that?  The screenplay, adapted from Billy Bob Thornton's original play, won an Academy Award.  It was also nominated for many others, including Best Actor (Billy Bob Thornton) and Best Picture.