Aspiring dancer Irene (Ginger Rogers) convinces vaudevillian Vernon Castle (Fred Astaire) to give up his comic act for something more serious: ballroom dancing. Together, they work on perfecting their dance routine and take the act to Paris. It's a rocky road at first, but, after a knockout appearance at the Café de Paris, the duo become a sensation. With their fame steadily rising, the Castles seem on top of the world. But the outbreak of World War I threatens everything.