The noble family de la Porte lives at castle Medan. After the lost heir August returns unexpectedly, countess Herm, mother-in-law of younger brother Johann, fears for the inheritance of her daughter. Together they antagonize the brothers. During a brawl, Johann gets shot by accident. August leaves his home for good, but beforehand he hides his papers of identity in the castle. Johann's oldest son is the next rightful heir, but due to his excessive deformity he is locked away to make room for his younger brother Gert. Years later, the dying August confesses to his daughter Agga their true identity. She travels to castle Medan to find the hidden papers and take possession of her legacy. On her arrival the countess instructs her nephew Gert to court Agga for the protection of the estate. However, she falls in love with neighbour Magnus and rejects Gert. Hence countess Herm and her nephew forge a plan to set Gert's brother, who is kept at the castle like an animal, on the uninvited guest.