 In 1915, Calhoun and Harrigan are struggling songwriters who team up with vocal talents Katie and Lily Blane. With the Blanes singing their songs, the writers become more prosperous and famous. Harrigan and Katie Blane become romantically involved and he writes "America, I Love You" which he promises she can introduce to the world. When the world-famous Nora Bayes asks to sing Katie s song, Harrigan cannot refuse. Upset at the broken promise, Katie leaves for London along with her sister. As their prosperity fades without the singers, the two men enlist in World War I and run into the sisters in England.