In Washington, D.C., S. Winthrop "Sam" Putnam, the officious Assistant Secretary to the Assistant to the Undersecretary of State, is embarrassed to discover that a letter inviting Ethel Barrymore to represent the American theater at the International Festival of the Arts in Paris was mistakenly sent to Ethel "Dynamite" Jackson, a Broadway chorus girl. Hoping to rectify the situation, Sam flies to New York to explain the mix-up to Ethel. Later, however, when he is lauded for his ingenious decision to represent the common man at the prestigious event, he re-invites her, enticing her with descriptions of a romantic Paris in springtime. On the French luxury liner to Paris, Ethel is surrounded by the other, distinguished, middle-aged, male festival representatives, who are all unabashedly haughty and determined that Ethel will not disgrace the U.S. with her natural ebullience. Also on the ship is Philippe Fouquet, a French entertainer and nightclub owner famous for his womanizing, who must work as a waiter for his return passage to France, as his money has been indefinitely frozen for back taxes in the U.S. On the last night of the cruise, Philippe rescues Ethel from lessons in using correct dining etiquette and French, and takes her to the shipboard ball, expecting that Sam, who is secretly smitten with her, will soon leave the stuffy group to join her. However, when ordered by his employer to return to the kitchen, the irrepressible Philippe convinces Ethel to go with him and soon has the French kitchen staff honorbound to show Ethel a good time. A joyous party commences, but when the delegation learns that Ethel is dancing in the kitchen, Sam is sent to inform her that she will be returned to the U.S. However, in the kitchen, Sam feels obliged to drink toasts to the U.S., France, and then every other country, so that by the time he meets up with Ethel, he has joined the dancing. At the end of the evening, Ethel and Sam know they are in love, but as Sam's engagement to his boss's daughter, Marcia Sherman, has already been announced in the Congressional Record , there seems to be no future for them. In spite of the obstacles, they decide to be secretly married by the ship captain, and Philippe makes the arrangements for them. Soon after, however, Philippe discovers that the "captain" was really François, a busboy who was stealing liquor from the captain's room when Philippe unwittingly interrupted him. Although Philippe wants to tell Ethel and Sam that their marriage is phony, François convinces him that, to avoid arrest, they must wait until the ship docks. The Frenchmen then booby-trap the couple's bedrooms to delay their marital bliss. After suffering from collapsing beds, self-opening doors and lights that turn on automatically, Sam and Ethel's attempts at a honeymoon are finally curtailed when his boss, Secretary Sherman, shows up to reprimand Sam for joining the kitchen party, and Ethel spends the rest of the night alone in the bathtub. After arriving in Paris, Sam discovers that Marcia has flown in to keep an eye on him. Though he has convinced the delegation to allow Ethel to remain, Sam decides, for the sake of the festival, to delay announcing their marriage, but his hopes for a smooth opening are shattered when, during a speech about peace and harmony, Ethel and Marcia begin slapping each other. Ethel is expelled from the festival hall, and walks off her frustration in the cold and wind of springtime Paris. When she encounters Philippe, he informs her that her marriage is not legitimate. The romantic Philippe realizes how much she loves Sam, and decides to help her get him back. Meanwhile, to avoid being alone with Marcia and her jealousy-inspired ardor, Sam agrees to attend a nightclub with the Shermans, unaware that it belongs to Philippe and that Ethel is the featured performer. Sam becomes jealous and wants to go backstage when he sees Ethel kiss Philippe at the end of their act, but Marcia threatens him with job dismissal if he does. Sam leaves after accusing her of wanting him for his White House potential, and Sherman, who is aware of Marcia's faults, backs him up. In her dressing room, Ethel rebuffs Sam and pretends to be having an affair with Philippe. Knowing that Sam is following her, Ethel follows Philippe to his apartment, where Sam is ready to fight Philippe. To Ethel and Sam's surprise, Philippe's wife Mimi shows up and they learn that Philippe's carefree Parisian demeanor is just a professional act, as he is secretly and happily married, with five children. Now Sam stubbornly accuses Ethel of consorting with a married man, but the Fouquets gently send the sparring lovebirds away. Out on the streets, Ethel and Sam continue their quarreling until daybreak, when, in sight of the Eiffel Tower, they make up.