Growing up in a coal-mining community in Philadelphia, Tommy and Jimmy Dorsey (playing themselves) are encouraged by their father, Thomas (Arthur Shields), to study music. The highly competitive siblings are soon playing with their father's band. As grown men, the Dorseys begin touring with their own ensemble, with childhood friend Jane Howard (Janet Blair) on vocals. Despite their rising success, the bickering brothers have a falling out, and Jane schemes to reconcile them.
There are cameo appearances by other musicians of the period: Paul Whiteman, Charlie Barnet, Henry Busse, Bob Eberly, Helen O'Connell and Art Tatum. The Jimmy Dorsey composition and theme song "Contrasts" is played in the movie. "Green Eyes", "Tangerine", "I'll Never Smile Again", "Marie", and "I'm Getting Sentimental Over You" are also featured in the movie, along with "To Me" and "Dorsey Concerto". Paul Whiteman and the Orchestra perform "At Sundown".