er Herrscher (The Sovereign) was based on Before Sunset, a play by Gerhart Hauptmann. The great Emil Jannings stars as Mathias Clausen, a self-made businessman who is forced to do a great deal of soul-searching when his wife unexpectedly dies. Determining to start life anew, he falls in love with his secretary Inken (Marianne Hoppe) and impulsively takes a vacation to Italy. Clausen's selfish grown children, not wishing to share their father's affections -- nor his money -- with his new wife-to-be, go to court demanding that Clausen be declared mentally incompetent. Upon finding this out, Clausen flies into a rage, leaving the audience to wonder whether or not he really as gone off his trolley. Der Herrscher was directed by Veit Harlan, more famous (or notorious) for his viciously anti-Semitic Jud Suess (1940).

Overview from themoviedb.org