The film begins with Magnolia, daughter of Captain Andy Hawks and his domineering wife Parthy, enjoying her childhood aboard her father's show boat. Parthy, irritated over the supposed influence of leading lady Julie (Magnolia's idol and best friend) fires her, despite her husband's objections. Many years later, Magnolia is a young woman and becomes a leading lady. Her leading man is Gaylord Ravenal, a riverboat gambler with whom she falls in love and elopes. But the sudden and unexpected death of Captain Andy forces the couple to leave the boat and move to Chicago rather than endure the disapproving Parthy, and Ravenal's gambling luck soon runs out. Then, Parthy announces she's coming to visit.