Flirting at the wrong time/wrong place can get a guy into big trouble. Niki (Chevalier), an officer with Vienna's Royal Guards, is romancing violinist Franzi (Colbert). During a visit by King Adolf (Barbier), his plain daughter Princess Anna (Hopkins) mistakes a smile meant for Franzi to mean that Niki is interested in her. Duty-bound, Niki is forced into a royal marriage. So the worldly Franzi decides to help Anna win her reluctant new hubby's love by turning her into a knockout.