Thornton plays a simple-minded man, Karl Childers, who has been in a mental hospital for murder for the past 25 years. On the day of his release, he is interviewed by a reporter, Theresa Tatum (Molly Ringwald), who is writing her article with the intent of examining whether criminals judged to be insane should be released. Before the interview, Tatum is of the opinion that criminals like Childers should never be released. During the interview, however, Tatum must question her previous beliefs in this matter.

The title of the film comes from Childers' description of the murders. He admits to committing murder with a "kaiser blade, some folks call it a sling blade, I call it a kaiser blade".