Based on the famous Scopes Monkey trial of 1925 a Tennessee school teacher Bertram Cates (Dick York) is arrested for teaching his students Darwin's theory of evolution. The case receives national attention and one of the newspaper reporters (Gene Kelly) arranges to bring in renowned defense attorney and atheist Henry Drummond (Spencer Tracy) to defend Cates. The prosecutor played by Fredric March is a former presidential candidate and famous evangelist. The two are old adversaries and clash throughout the film. The situation is further complicated by the fact that Cates's girlfriend is the daughter of the town's bombastic preacher (Claude Akins).Throughout the movie the sarcastic Kelly mocks the bible toting hostile townsfolk. Tracy eventually calls March to the stand and prods him to explain various biblical stories such as Jonah and the whale. Eventually, the great Biblical Literalist is forced to concede that certain Biblical accounts cannot be taken literally, but must be interpreted intellectually. With that concession, Drummond is able to assert Cates has every right to hold a differing opinion, including about the Book of Genesis and to deny him that right is unjust.March is so rattled by Tracy's questioning that he collapses under the strain. In the end despite his badgering of March, Tracy is sympathetic to March's beliefs. The judge (Henry Morgan) issues a $100.00 fine much to the dismay of many in the courtroom.