Harold Hill, a con man, goes to River City, Iowa and tries to make money by starting a boy's band. He is helped by sidekick Marcellus Washburne. Most of the town is taken in by him, including Winthrop Paroo, a boy with a lisp. Hill also forms the school board into a barbershop quartet and organizes a lady's dance society led by town busybody Eulalie Shinn. However, some people are suspicious of him. One of these people is Mayor Shinn, who owns the pool hall that Hill blames for the serious trouble River City is in. The other is music teach and librarian Marian Paroo. Hill tries to woo Marian, but has no luck.