Katharine Hilliard, mousy dean of a stuffy music school, meets and is insulted by swing band leader Barry Clayton on a train. To "show" him she takes a friend's advice, removes her glasses, and puts on a designer gown. Naturally, she becomes gorgeous. Soon, both Barry and crooner Jimmy Hale are after her, and she finds herself in the midst of triangles and misunderstandings.

Songwriters Calhoun and Harrigan get Katie and Lily Blane to introduce a new one. Lily goes to England, and Katy joins her after the boys give a new song to Nora Bayes. All are reunited when the boys, now in the army, show up in England.