Don Alejandro and Don Diego visit their friend, Don Alfredo, to encourage him to sign an oath of solidarity with all the dons against the Eagle's plot to take control of California from Spain. Alfredo is concerned the oath will put him in danger, but Alejandro and Diego promise no harm will come to him. Alejandro leaves for Monterey to petition the Governor. Garcia then informs Diego that Administrado Jose Sebastian Varga will arrive to take over the de la Vega hacienda. Diego suspects Varga is involved in the Eagle's plot to take over Los Angeles, and considers defending the hacienda to the death as himself rather than as Zorro. But Bernardo convinces him to use this opportunity to spy on the Eagle instead. Varga and his assistant Juan Greco arrive to take over the hacienda. Varga informs Diego that he is aware of the work he is doing with his father to organize resistance against enemies of the King. Diego is angered when he is put under house arrest and has difficulty stopping himself from fighting like Zorro. Diego and Bernardo use the secret passages to spy on Varga and Greco. Diego and Bernardo watch them search the hacienda for secret passages where Don Alejandro might have hidden the list of dons who signed the oath. Varga discovers the list in a secret drawer, but is captured by Zorro before he can read it. Garcia discovers Zorro in the hacienda and chases him out. Zorro fights his way up to his room, changes out of his costume and sends Bernardo off dressed as Zorro. Diego convinces the soldiers that Zorro escaped. Later Diego examines the papers he confiscated from Varga, and finds a letter written by the Eagle that has not been posted through the mail. Diego realizes that Varga is the Eagle.