In Rome, Monticelso and Francisco prepare to charge Vittoria with the murder of Camillo. The Register and the Chancellor prepare the scene for the trial while Monticelso and Francisco talk about their plan to ruin Vittoria’s reputation, even though they have no real evidence that she is guilty. As these men leave, Flaminio enters with Marcello and a lawyer. The lawyer criticizes the brothers, claiming that their sister Vittoria will be easily convicted if anyone can prove that she “but kissed” Bracciano. Flaminio turns the lawyer’s comments into sexual jokes as a way to distract from his own role in the murder. Marcello is miserable. He criticizes his brother for helping Bracciano and Vittoria in their immoral acts. Flaminio defends himself, claiming that he wanted to help the family. He claims that Marcello works for Francisco for a pitiable amount, and this comment prompts Marcello to defend himself and insult Flaminio.

A number of foreign ambassadors enter. They will be the judges at the trial. The Savoy ambassador and the French ambassador take their seats. Flaminio makes jokes with the lawyer, alleging that the French ambassador impotent. The English ambassador and the Spanish ambassador enter, and Flaminio mocks them, too.