A diplomat's daughter in Paris turns a fact-finding mission into a non-stop party.

Senator Jonathan Cartwright and his wife arrive at the American embassy in Paris, France, on a mission to make that city off-limits to American enlisted men. Ambassador William Fiske and his daughter Joan welcome their guests but are opposed to the idea. While Joan gives Mrs. Cartwright a tour of the city and introduces her to her fiancé, Prince Nicholas Obelski, Fiske receives another visitor, Gen. Andy Harvey, whom he hopes to enlist in opposing Cartwright's plan. Later that day, enlisted men Daniel Sullivan and Albert O'Connor use their wits to get into a benefit fashion show at Christian Dior, the proceeds of which will be donated to the Red Cross. Danny and Al are seated near Obelski, Fiske, Harvey and the Cartwrights, all of whom observe the soldiers' uncouth behavior. When the soldiers flirt with Joan, who is working as a model in the show, she pretends to be French and warns them that the general is nearby. The soldiers decide to leave but complain about their expensive bill. To avoid reinforcing Cartwright's case against American soldiers, Joan intervenes and escorts Danny and Al outside. Afterward she explains to her guests that the soldiers were unaware there was a cover charge, and she and her father pay their bill. When Danny slips back in to ask her on a date, Joan decides to go out with him in order to prove Cartwright wrong, as he had wagered that she would slap the soldier within thirty minutes of a date with him. Although her father and Nicholas disapprove, Mrs. Cartwright playfully poses as Joan's employer and, after meeting Danny and Al, gives her consent for Joan to go out with Danny. When Danny discovers his wallet is missing outside the Eiffel Tower, he accuses Joan of being a pick pocket. Joan is so angry at his accusation that she drops her fake accent. After Danny finds his wallet in a taxi and demands an explanation, Joan claims that she is working in France without a visa and uses the accent as a cover. By dinner time, Joan has fallen in love with Danny and invites him to join her at the ballet the next night. Although she has an extra ticket, Danny insists that he will buy tickets for both of them. After spending an enjoyable evening at numerous nightclubs with Joan, Danny offers to buy her an airplane ticket home so she can visit her supposedly sick father, as well as Danny when he returns stateside. Joan is touched by his thoughtful gesture and, after his wallet goes missing for real and the maitre d' threatens to have Danny arrested, Joan leaves to get some money. When she returns to the embassy she tells everyone about Danny's kindness. However, Al, who is at the embassy with the others, has drunkenly revealed moments earlier that a common soldier's ruse to "get a woman" is to buy her a fake airplane ticket. Joan is disappointed but not convinced that Danny is a cad, so she decides to keep their date to meet at Notre Dame the next afternoon. After Fiske calls in a favor to the nightclub owner and arranges for Danny's bill to be paid, the police return his wallet, which has been found. The next day, Danny buys tickets to the ballet as well as an airplane ticket for Joan, then goes to Christian Dior in hopes of seeing her. Joan is not among any of the models, but arrives with Cartwright, who wants to buy his wife a gift. When Danny sees Joan alone with the older man and overhears her sweet-talking him into purchasing a dress, he assumes the worst about her. As a result, when they meet later, he takes her to a restaurant near her hotel and makes several suggestive remarks. After spilling wine on Joan's dress, another apparent ruse that Al had warned her about, Joan and Danny trade insults and she leaves. When Joan, now thoroughly disappointed, returns to the embassy and admits defeat, Mrs. Cartwright suspects that she has fallen in love. Al, meanwhile, returns to the hotel room he shares with Danny but has been sworn to secrecy about Joan's ruse by Harvey. The next evening, Al takes Danny to the ballet and, through his binoculars, sees Joan and the group in their box seats. During the performance, Danny tells Al about seeing Joan at Dior with an older man, and Al realizes this explains his friend's mistreatment of Joan the night before. Al then secretly goes to the embassy box and tells everyone what happened. At intermission, Danny refuses to acknowledge Joan when he sees her with Cartwright. Mrs. Cartwright stays in the lobby during the second act and, maintaining the guise of Joan's employer, tells Danny a story about Cartwright to provoke Danny's jealousy and protective instinct. After the performance ends, Danny insists that Joan leave Cartwright, presents her with the airplane ticket, and proposes to her, then takes a swing at Cartwright. Al faints, and Joan, who delightedly accepts Danny's proposal, apologizes to a disappointed Nicholas. When Danny learns the truth about Joan and the group, he rescinds his proposal and leaves. Joan steadfastly insists they will marry and the next day, while Danny is working guard duty and is under orders not to speak, Joan tells him he has no recourse and that they will be married in June. They then kiss, and a wedding soon follows.