Nazi historical drama about Duke Karl Alexander of Württemberg and his treasurer Süß Oppenheimer.

Country Dr. Robert Koch is desperate: a tuberculosis epidemic is decimating the children in his district and no one is able to do anything about it. Every fourth child is already sick and the parents must helplessly watch as their young ones die. Now Koch is undertaking to find the cause of the tuberculosis --- something he has already been working on for years --- which has been causing this plague of illness. His work is made more difficult by envy; for example, that of his teacher, who was wounded defending his honor. But his greatest obstacle is the famous Berliner scientist and Reichstag deputy, Privy Councilor Rudolf Virchow: He is extraordinarily skeptical of Koch's theory, that the cause for tuberculosis is a bacteria.

Lilian Harvey plays a young heiress in long-ago France named Madelon who is raised by her grandfather as a boy in order to frighten away fortune hunters. But when the old man dies, her guardian Cesaire wants to marry her off to the rich prefect Barberousse. She is tricked by Cesaire with the portrait of a young man (Viktor von Staal) which is presented to her as that of her future husband. But when Madelone discovers this scheme she flees, again in men's clothing. But on her route to escape, she meets the young man from the portrait and falls in love with him. But Madelone can't give up her disguise right now...