A young man, Bert Cates, is arrested in a small Bible Belt town for teaching the theory of Evolution in the public school. Two of the finest legal minds in the U.S. are called to the trial: Henry Drummond for the defense, and Matthew Harrison Brady for the prosecution. The trial proceeds on three levels, the guilt or innocence of Cates, the issue of the Bible vs. Darwin, and finally, the personal confrontation between Drummond and Brady.