New York, 1917. Big time producer Florence Zweibach is putting on a Broadway show, and lots of hopeful girls long to be part of it. On the way to the audition, Mary Conklin, a sweet, budding ingenue, meets Harry Harrigan, a down-and-out Tin Pan Alley tunesmith, and the romantic sparks start to fly. To escape loan sharks, Harry enlists in the war that's just broken out in Europe, leaving Mary behind with his portfolio of sheet music and the dream of what might have been. Zweibach stars Mary in his patriotic revue and even falls in love with her, much to the chagrin of his fiancee. But the revue is a big flop until Mary pulls out one of Harry's songs, "You're a Grand Ol' Flag." Harry returns from the war to discover he's a celebrated songwriter and he and Mary are blissfully reunited. The fireworks explode like the Fourth of July in this all-American musical featuring some of the best songs of George M. Cohan, including "I'm a Yankee Doodle Dandy," "Over There," "Give My Regards to Broadway," "Harrigan," "Mary" and many more!