Claudio is married to Cesarina, a frivolous and unfaithful woman. After the death of their only son their marriage is cold. While his wife lives her free life, Claudio is dedicated to the development of sophisticated weapons, elaborating the project of a new cannon; but smitten by the virtuous Jew Rebecca he can not surrender to his feelings because his religion prevents him from getting a divorce.
Young aviatrix Lyda spurns the advances of the Prince of Sèvre and falls in love with journalist Mario, who, although engaged to Cesarina, goes to Lyda's home. Cesarina sees them and manages to persuade Mario to leave Lyda.
Grand Duchy of Wallenstein. Elsa Holbein is the young beautiful daughter of General Julius, the Chief of the General Staff. After a spy named Moise Sthar steals military documents, Julius is accused of betrayal. He kills himself while Elsa is forced to leave. Homeless, she begins wandering the streets until, on the Riviera, she starts her performing career under the pseudonym of Diana Cadouleur and becomes a successful actress and singer. One day, in a small church, she meets an elegant young man and she falls in love with him. But during a tour on the Lucarno Lake she runs into Sthar who, rejected by Elena, spreads rumors about Prince Massimiliano’s behavior.