Bert's the kind of guy your father warned you about—a rebel. But Rachel, a preacher's daughter, is kind of in love with her friend, Bert, anyway. She goes to visit him in jail. He seems like a nice enough guy, and he's not a dangerous criminal, after all.
Unless you count threatening an entire belief system as dangerous. In that case, he's almost a terrorist. See, his crime is teaching evolution in a public school, which is against the law. Rachel's father, Reverend Jeremiah Brown, is one of Bert's biggest opponents, and most of the townspeople follow the Reverend's lead.
Two important lawyers roll into town for Bert's high-profile trial. For the prosecution, there's Matthew Harrison Brady, a three-time presidential candidate (no-time winner)—we're thinking a George Clooney type. For the defense, there's Henry Drummond, who used to be friends with Brady and is a famous agnostic—we're thinking Matthew McConaughey, yes?
Truly the talk of the town, Rachel's father, Reverend Jeremiah, whips everyone into a fury over this whole evolution business through song, sermon, and prayer. He wants to get all of the townspeople on his side before the trial starts.
Rachel doesn't know where she stands. She is frightened of her father and doesn't really like the idea of descending from monkeys. But she also respects Bert.
When the trial begins, it's the biggest show the town has ever seen. Several people are called to the stand to testify, including Rachel. She ends up speechless, because she doesn't want to lie but also doesn't want to send Bert to the slammer. Conundrum.
The judge seems to favor Brady's side heavily, and won't let Drummond use any of his experts as witnesses. So Drummond ends up free-stylin' and calls Brady himself to the stand. He ties him up in some rhetorical knots, and ends up making a fool of his old buddy.
The town fills with reporters as the verdict is about to come down. So what's the verdict? Bert's guilty. But the judge only orders him to pay a fine of one hundred bucks.
Brady is spitting mad about this, because he wanted to make an example of Bert and lock him away for a good, long time. Drummond, who is looking to appeal the case at a higher level, says his client won't pay. So the judge orders him to pay five hundred dollars.
Brady was planning to make a big speech, but since the case concluded kind of anti-climactically (no ball and chain for Bert), he has to scramble for an audience. No one really pays him any attention, and he ends up collapsing and dying. Now there's a climax for you.
Hornbeck, a smart aleck reporter, pays the five hundred bucks Bert owes. Drummond, who ends up feeling sorry for his opponent, is disappointing to Hornbeck, who is out for blood. The two argue about whether or not they should have any sympathy for Brady.
Bert, Drummond, and Rachel all get out of town on the last train. Science triumphs, having only had to pay a few hundred buckaroos to exist in schools.