The Student Prince is a 1954 American musical film directed by Richard Thorpe and starring Ann Blyth, Edmund Purdom, John Ericson, Louis Calhern, Edmund Gwenn, S. Z. Sakall and Betta St. John. The film is an adaptation of the 1924 operetta of the same name composed by Sigmund Romberg with lyrics by Dorothy Donnelly. The film's screenplay was written by Sonya Levien and William Ludwig. Based on the stage play Old Heidelberg by Wilhelm Meyer-Förster (itself an adaptation of his obscure 1898 novel Karl Heinrich), the film is about a brash young prince of a small German kingdom who must choose between his romance with a barmaid and his impending royal duties. It was filmed and released in CinemaScope and Ansco Color. During production, original star Mario Lanza left the project before principal photography, necessitating his last-minute replacement by the lesser-known Purdom. Because of the contractual agreement between Metro-Goldwyn-Mayer and Lanza, songs that the Lanza had recorded were dubbed over Purdom's voice. Plot Near the turn of the 20th century, young Prince Karl of Karlsburg, a small but fiercely proud kingdom within the German Empire, is the grandson of one of a handful of petty kings within German-speaking central Europe. Karl has been raised most of his life for the military, but when it comes time for him to marry, the princess who has been picked for him cannot stand his stiff formality. His tutor recommends that he be sent to a university in Heidelberg to develop an easier, more sociable manner. He eventually slips into the social mix at the university, becomes accepted by his peers and falls deeply in love with Kathie, a pretty, popular and musically inclined barmaid who holds court in the local biergarten. When his grandfather dies unexpectedly, Karl must marry the princess and take his place in Karlsburg. He returns to Heidelberg one last time to bid Kathie a poignant farewell. Cast Ann Blyth as Kathie Ruder Edmund Purdom as Prince Karl Mario Lanza as Karl's singing voice John Ericson as Count Von Asterburg Louis Calhern as King Ferdinand of Karlsburg Edmund Gwenn as Prof. Juttner S.Z. Sakall as Joseph Ruder (credited as S.Z. "Cuddles" Sakall) Betta St. John as Princess Johanna John Williams as Lutz Evelyn Varden as Queen John Hoyt as Prime Minister Richard Anderson as Lucas Roger Allen as Von Fischtenstein Steve Rowland as Feuerwald Chris Warfield as Richter Gilbert Legay