One Should Be Twenty Again (German: Man müÃÂte nochmal zwanzig sein) is a 1958 Austrian comedy film directed by Hans Quest and starring Karlheinz Böhm, Johanna Matz and Ewald Balser. It was shot at the Sievering Studios in Vienna. The film's sets were designed by the art director Fritz Jüptner-Jonstorff. It is a remake of the 1943 German film An Old Heart Becomes Young Again directed by Erich Engel and starring Emil Jannings.
The wealthy owner of a chocolate factory Friedrich Hoffmann is a celebrated bachelor. However, when he discovers that an illicit affair in his youth led to the birth of a child and that he now has a granddaughter Susanne. His nephew Paul unwittingly hires Susanne as his secretary and falls in love with her. Unaware of why Friedrich is doting on the young woman, Paul fears his intentions towards her are romantic.