Maria de Rudenz falls in love with Corrado against her father's wish and flees with him to Venice. Being there, Corrado suspects that Maria is unfaithful to him, abandons her, returns to the Rudnez Castle area and falls in love with Maria's cousin Mathilde.
Maria manages to return to her ancestors Castle, discovers that her lover is not only going to marry her cousin, but that in fact he is not who he is but the son of a murderer. She is ready to keep this secret safe and sound with her if only Corrado returned back to her but he refuses and in a rage injures her with his sword so that everyone thinks that she is dead.
On Mathilde and Corrado's wedding day Maria appears again, discovers his secret to everybody, murders Mathilde and commits a suicide.