The film opens with naval scenes and a chorus of WAVES singing ‘The Navy Song’ on stage, and continues with a sister act, the Allison Twins (both played by Betty Hutton), singing the same song in a night club. Identical, except that one is blonde the other brunette, they are temperamentally very different. Susie, the blonde, is brash and scatter-brained, while Rosemary is serious and reliable. They leave their night club job to join the WAVES although Susie is extremely reluctant to do so. She is infatuated with popular singer Johnny Cabot (played by Bing Crosby) and fears that by joining the service she will never be able to meet him. Taking her collection of his records with her, however, she locks herself in the barracks washroom and plays Johnny’s record of ‘Moonlight Becomes You’.