Con man Harold hill travels to the small town of River City, Iowa to earn his fortune. He decides to convince the town that they need a boys' band and then plans to run away once the boys have paid for instruments and uniforms. He even claims to be a professor of music. His scheme is moving along perfectly until Harold falls in love with the town librarian and piano teacher, Marian. Even though she knows that he's a con man, she still loves him for the hope that he brought to the town. When another saleman comes to town prepared to spill the beans about the conman, Harold decides to stay and face the music. After being arrested and then the town standing up for him, the band comes in, in full uniform with their instruments. Harold conducts the band to play their first, though bad, number. The parents are delighted and proud of the music and quickly forgive the "professor".