The musical opens at Madame Dubonnet’s finishing school on the outskirts of Nice, France. Five young British girls (students at the school) are dreaming and chatting of the ball that evening—and of their hopes for boyfriends. Nancy hopes to pair off with Pierre, Fay with Marcel, Dulcie with Alphonse, and Maisie with the rich and handsome American Bobby Van Husen. Polly (the original “poor little rich girl”) has invented an imaginary boyfriend that writes to her from Paris because her wealthy and widowed father has forbidden her to date for fear that all boys are after only her money. Of course, Madame Dubonnet is not above dreaming of lovers herself. When she hears that Polly’s father, Percival Browne, will be visiting that very evening, she begins to wonder if he is handsome and rich--and available.
As the girls disperse, Bobby sneaks in the back way and surprises Maisie. He has come to ask her to save every dance that evening. She hints that she may honor his request then rushes him out before someone catches them together and alone.
Next enters Percival Browne, looking for his daughter; but he finds Madame Dubonnet first. They soon remember each other from a fling during the war, when they are both younger. The old sparks ignite quickly, and they are about to kiss when they are interrupted by the girls’ laughter off stage; so they rush out, paired up once again.
Polly enters, followed soon by Tony, dressed as a messenger boy with a package for Polly. They begin to fall for each other, and Polly soon invites him to the ball with her that evening, although she knows full well her father would not approve of someone from such an obviously lower station in life.
In the next act, that same afternoon, Lord and Lady Brockhurst enter the scene, bemoaning the fact that their only son, Tony, has run away from college. Lady Brockhurst is a very proper British matron, but her husband is a bit of a scalawag, with an eager eye for all the beautiful women around him. They leave the scene and Polly and Tony reenter, with both telling the other that they have no money and want only to love each other and lead a simple life. They become the final boy/girl mix in what then becomes a hilarious festival of song and dance as they work out the various obstacles to their loves (parents, social customs, and their own hesitations).
That evening at the ball everything is untangled: The young lovers (Nancy and Pierre, Fay and Marcel, Dulcie and Alphonse, and Maisie and Bobby) all become engaged to marry. Polly and Tony find out the truth about each other (each is cultured and well-to-do) and announce their engagement. Percival and Madame Dubonnet decide they should marry and rekindle their own romance. And Lord and Lady Brockhurst are reunited with their son (and soon-to-be daughter-in law) and realize that even they love each other. The plays ends to the strains of “I know that I could be happy with you, / My darling, / If you could be happy with me.”