Mirabel Miller, a stenographer living in a small town, wins five thousand dollars in a Casaba melon sweepstakes. Dissatified with her drab life, and having recently adopted the motto "everything or nothing," Mirabel decides to go to New York and spend the money on clothes and fancy hotels against the advice of her banker, vowing to live for a month without regard to what happens afterward. At the exclusive Walsdorf-Plaza in New York, she is mistaken for a rich society girl. Meanwhile, Prince Allesandro of Allesandria, unknown to anyone else, has gotten a job as a bellboy in order to learn about American hotels. As Sandro assists Mirabel with her unpacking, he incites her animosity when he takes unsightly trimming off one of her new hats. Mr. Squires, the chief bellboy, fires Sandro, and he returns to the Allesandria consulate, where Consul-General Semanek is surprised to see him days before his scheduled and much-publicized visit. Sandro goes back to the Walsdorf-Plaza, where he again insults Mirabel's taste. Although Mirabel, who has spent her days in New York going to movies alone, is about to leave town in disappointment, Sandro convinces her to dine with him at an Italian restaurant, where she reveals to his delight that she is not the wealthy girl others mistakenly think she is. Their romantic dinner is interrupted, however, when Sandro is called outside, and Semanek and his cohorts abduct him. When Sandro finds Mirabel again at the hotel, she refuses to speak to him. Cordelia Channing, a society belle staying at the hotel, calls Mirabel to invite her to a charity ball she is giving that evening. Mirabel is impressed with the title of Cordelia's boyfriend, Lord Clewe, and becomes excited in the belief that she will attend the party with the couple; however, later she sadly realizes that she has not been invited to sit with them and must provide her own escort. Sandro arrives and promises Mirabel that she will attend the party with a prince, but when she arrives at the ball to discover that the prince is none other than the bellboy, she becomes angry again. The guests, however, acknowledge Prince Allesandro and offer him and Mirabel seats at the main table. Although Mirabel does not believe that Sandro is a prince, she goes along with what she believes to be a ruse. As the couple dance, certain guests recognize various articles of clothing on Sandro that he stole from them to attire himself for the occasion. Sandro and Mirabel are then chased out of the ballroom, and the police arrive to arrest him as an impostor. Believing that Sandro performed the impersonation for her benefit, Mirabel goes to the jail to try to get him out, and although she does not succeed, Sandro overhears her say that she loves him. Semanek agrees to get Sandro out of jail if he will go with him immediately to the docks to attend his welcoming ceremony to the country. Mirabel comes to the harbor to try to have the prince intercede for Sandro, but when she finally realizes that he truly is the prince, she flees back to the hotel. Sandro makes a grand entrance there, to the surprise of his former employers who earlier fired him, and finds Mirabel in the elevator. They then kiss as Sandro removes more trimming from her silly hat.