In 1961, Clarence Earl Gideon (Henry Fonda) is arrested on charges of petty theft. Unable to afford an expensive lawyer to defend him, he is forced to represent himself and receives a five-year prison sentence. He becomes a model inmate and jailhouse scholar, focusing on the Fourteenth Amendment, which guarantees U.S. citizens the right of due process. With the help of an attorney (Jose Ferrer), Clarence makes a startling discovery that changes everything. The film is based on a true story.