When a visiting American senator decides to make Paris off-limits to enlisted military personnel, the daughter of the United States Ambassador to France decides to show him that American servicemen can be gentlemen by dating one of them without revealing her lofty social status. Sergeant Sullivan takes Joan to colorful nightclub cabarets, and on a comical trip up the Eiffel Tower, all the time believing her to be a Dior fashion model.
Thinking she has an emergency back in America, Sullivan offers to buy her an airline ticket, for which she is grateful, until she hears that counterfeit plane tickets are a common scam used by American servicemen to impress girls. Sullivan's friend, the homespun Corporal O'Connor, all the while is a guest of the Ambassador's family and other top brass, and tries to alert Sullivan as to Joan's true identity, but is unable to contact Sullivan (and is sworn to secrecy).
When Sullivan drops into the Dior fashion show one day to look for Joan, he discovers that the staff have never heard of her. However he sees Joan observing the show with her father's friend, the Senator, whom he mistakenly assumes must be her sugar daddy. On their last dinner date, Joan walks out on Sullivan, when he accidentally spills wine on her and offers to take her to his hotel room, thinking he is dishonorable. Finally, one evening Sullivan and the Ambassador's family, by coincidence, separately attend the same ballet performance of Swan Lake, where during the intermission Sullivan learns her true identity and their misunderstanding is resolved.
Olivia de Havilland as Joan Fisk
John Forsythe as Sergeant Danny Sullivan
Myrna Loy as Mrs. Cartwright
Adolphe Menjou as Senator Jonathan Cartwright
Tommy Noonan as Corporal Al O'Connor, Danny's friend
Francis Lederer as Prince Nicholas Obelski
Edward Arnold as Ambassador William Fisk
Minor Watson as General Andrew Harvey. This was Watson's last film.