Jo Hayden (Judy Garland) and Harry Palmer (Gene Kelly) are a struggling vaudeville act with hopes of making it big. When success seems right around the corner, Palmer is drafted into the army at the advent of World War I. Thinking quickly, Palmer injures his hand to avoid being called to duty, but Hayden -- whose brother died in the war -- finds his action cowardly and breaks up the duo. Now, Palmer must figure out a way to bring them back together, even if it means going to war.