With their act about to come to a close, the Allison Twins (Betty Hutton, THE PERILS OF PAULINE) plan to go their own ways... well, one of them does. Level-headed Rosemary is planning to to join the WAVES (Women Accepted for Volunteer Emergency Service). Scatterbrained Susie, on the other hand, can only think of meeting her dreamy crooner Johnny Cabot (Bing Crosby, THE BELLS OF ST. MARY'S); but she nevertheless follows her sister and enlists (and proceeds to drive Rosemary and her fellow recruits batty by playing Cabot's records incessantly). During their liberty, Rosemary surprises Susie with tickets to the premiere of Cabot's new film Black Magic which will be preceded by an appearance by the singer. Put off by the "cheap and childish emotionalism" of Susie and the other screaming and fainting females in the audience, Rosemary takes an instant dislike to Johnny when she and Susie meet him in person at a club as a mutual friend of Corporal "Windy" Windhurst (Sonny Tufts, THE CROOKED WAY). Coming from a military family and having lost his father in the first world war, Johnny was eager to enlist but rejected due to his colorblindness. When the regulations ease, Johnny joins with the added bonus of getting away from the female fans who mob and maul him every where he goes. Upon learning that Johnny has joined the navy, Susie manages to get herself and Rosemary stationed at the same San Diego base. It soon becomes apparent, much to Windy's jealousy and Susie's devastation, that Johnny only has eyes for Rosemary despite her coldness. Making himself a third wheel on a date between Windy and Rosemary, Johnny pulls a prank on Windy that gets him confined to quarters. During a late night walk and a musical number, Johnny manages to prove to Rosemary that he is a deeper and more serious man than she believed.

Susie goes from jealous to absolutely devastated when Rosemary tells her that Johnny will soon be shipping off on a destroyer so she writes a letter to the Welfare and Recreation department pitching Johnny to create and produce an entertainment program for the WAVES recruitment effort. Johnny is shocked to be promoted to CPO in the WAVES which will prevent him from shipping out and recruits Windy to assist him under the impression that it was an act of retaliation. When Windy discovers that Susie was behind the letter, he blackmails Susie into helping him split up Johnny and Rosemary so that they can both have their chances with them. Having come to believe (with Windy's help) that Johnny was behind the idea, and that his talk of wanting to serve in the navy was all talk, Rosemary is as eager to transfer out of the program and away from Johnny as he is to finish the hybrid film/stage show in time to ship out. Not one of the better Crosby musicals by a long shot, the film's black and white lensing when most musicals were in Technicolor gives it the look of the recruitment film it essentially is. Characterization is often broad and motivation glossed over in musicals, but here the love story seems most perfunctory so as to make the machinations of the two antagonists seem more vile than just manipulative. The film was the third of Crosby's musicals in which he did a number in blackface (while singing "Ac-Cent-Tchu-Ate The Positive" on stage during the WAVES performance). The film's non-military costumes were designed by Edith Head (TO CATCH A THIEF and the twin effects were the work of effects cinematographers Gordon Jennings (THE LOST WEEKEND), Paul K. Lerpae (THE WAR OF THE WORLDS), and Farciot Edouart (VERTIGO). Yvonne de Carlo (CRISS CROSS) is among the uncredited WAVES.