The story spans about 40 years, beginning aboard the show boat Cotton Blossom in the 1880s, on the Mississippi River near Natchez, Mississippi. A riverboat gambler, Gaylord Ravenal, comes aboard and is taken with Magnolia, an aspiring performer and daughter of the ship's captain and owner, "Cap'n Andy". Magnolia is smitten with Ravenal as well, and seeks advice from Joe, one of the workers aboard the boat.
A local sheriff comes aboard and insists that the show not go on, because the star of the show, Julie, is a mulatto woman married to a white man, and local laws prohibit miscegnation. With the star gone, Magnolia and Gay(!) fill in. He later confesses his love for her and proposes.
Years later, Gay and Magnolia are married and living in Chicago with their daughter, Kim. Gay's gambling debts get out of control and he abandons his wife. Magnolia seeks a singing job to support herself and Kim, and tries to get a job at a club where she finds Julie, along with Frank and Ellie (two other performers from the Cotton Blossom) working. Julie sees Magnolia's desperate situation and abandons her position so that Magnolia can fill it.
On New Year's Eve, Andy comes to the club, unaware of Magnolia's troubles, only to discover her nearly being booed off stage. He rallies the crowd to her defense in a grand sing-along. He brings her back to the Cotton Blossom, where a changed and repentent Gay waits to be reunited with his wife and daughter.Plot Synopsis