Small town music teacher Ellen Evans loses her job when talented New York photographer Jerry Hendricks publishes a compromising, albeit innocent, photograph of her posing with the town drunk. Ellen goes to New York City to file a formal complaint against Jerry, who never obtained a signed release from her, but her sister Kay, a beautiful bargain basement model, insists on taking the matter into her own hands. Jerry fears losing his boss's recommendation for the Signal Corps if he finds out about Ellen's photograph, so he impersonates the vice-president of the magazine and promises to get Kay an introduction to the famous modeling agent John Robert Powers if Ellen will sign the release. Ellen signs the release only after she realizes that meeting Powers would fulfill her selfish sister's lifelong dream. However, as Jerry has lied about his friendship with Powers, he only gets in to see him when he pretends to be an air raid warden. Jerry then tricks Powers into meeting Kay, and Powers is so impressed with her that he hires her to train in his modeling program. Jerry is later arrested for arson because he set a fire in Powers' office as part of his imposture. He is deeply touched when Ellen pays his bail, and they fall in love after she sees his more artistic photographs. Kay, meanwhile, progresses through Powers' modeling school and is introduced at a preview party as the top "Powers Girl" of 1943. Ellen prepares a surprise party for Kay later that night at their apartment, but Kay insists that Jerry stay with her at the nightclub so that she can land a contract with a big cosmetics firm. Although Jerry thinks of Kay only as a "sister," Kay gets him hopelessly drunk and tries to seduce him. Kay's friends, Nancy and Googie, advise Ellen of her sister's subterfuge, but Kay and Jerry never show up for the party. Ellen is shocked when she calls Jerry's apartment late that night and Kay picks up the telephone. Ellen challenges her sister, vowing that she will no longer allow her to take everything dear to her. The next morning, Jerry receives his enlistment notice from the Signal Corps, and his friends, famous clarinetist and band leader Benny Goodman and singer Dennis Day, plan a farewell party for him. Ellen rents a glamorous dress and a handsome foreigner, Vandy Vandegrift, to make Jerry jealous. When Jerry's parents attend the party, they assume that Kay is his fiancée. Ellen rebuffs Jerry, who is completely unaware of the rivalry between the sisters, and when he picks a fight with Vandy, Vandy knocks him out. Vandy is horrified, however, when he learns that Jerry will soon be his superior officer in the Signal Corps, and revives Jerry by telling him that Ellen sincerely loves him. The next morning, Jerry and Ellen marry at the courthouse, and Jerry immediately leaves to report for duty.