In Renaissance Rome, the captain of Strozzi mercenary kills the banker Chigi that has refused the hand of his daughter Berta, girlfriend of Giuliano de 'Medici, brother of Cardinal Giovanni. Accused of the crime is instead the young Julian, who is arrested and locked up in jail while awaiting trial. Meanwhile the real murderess unashamedly confesses the crime to Cardinal Giovanni, who can not violate the secrecy of confession remain helpless before the judges who condemn him to the gallows. But shortly before the Cardinal with a ruse it shall enable the Strozzi to confess the crime in the presence of witnesses hidden. Giuliano is immediately released and can then marry his Berta.