Beverly Calhoun, an American college girl, discovers that her Cousin Oscar is the heir to the throne of Graustark, a European kingdom, and joins him there. They are met by the Duke Travina, the temporary regent. General Marlanx, pretender to the throne, learning of the young prince's arrival, plots with Saranoff to assassinate him. In the Alps, Oscar is injured while skiing, and the duke suggests that Beverly wear Oscar's uniform and impersonate him until he recovers; Saranoff's plot is thwarted by Danton, leader of a group of shepherds. Danton becomes her constant companion and guard, and she obtains women's clothing to charm him. Confusing her as a rival to the "prince," Danton jealously challenges the prince to a duel. Oscar reveals the impersonation to Marlanx, but Danton, acknowledging himself to be the prince of a nearby kingdom, exposes the pretender's plot and wins the hand of Beverly.