What does Cosimo tell Biagio about their uncle's activities and what does he want to do about them?

Cosimo confides in Biagio, and in several versions to the people of the town, that he frequently sees the Cavalier, normally not social, walking to the ports late at night. There he meets men wearing turbans and talks with them in great detail about the schedules of the boats and what cargo each will be carrying. When he is sure of his half-uncle's status as the most miserable of traitors, he devises a scheme to catch him and the pirates in the act and expose them all.