Bracciano, Camillo, Flaminio, and Vittoria enter, carrying torches and accompanied by several unidentified gentlemen. After welcoming Bracciano to Rome, Vittoria leaves with her husband, Camillo. Vittoria’s brother Flaminio whispers privately in Bracciano’s ear, promising him that his “happy sister,” Vittoria, has arranged to meet him later. Flaminio tells the men with the torches to leave. When he and Bracciano are alone, he speaks openly, stating that Vittoria is in love with Bracciano. Vittoria’s servant, a Moor named Zanche, will help to arrange for Bracciano and Vittoria to meet in private to consummate their affair. Bracciano signals his desire for Vittoria, and Flaminio mocks Camillo, suggesting that the man is unable to satisfy Vittoria in bed. He suggests that Camillo has syphilis and is old and unromantic. Flaminio states that Vittoria and Bracciano would be better suited for one another and offers to help them conduct the affair. Flaminio hears Camillo approaching, so he hides Bracciano in a closet.

To himself, Flaminio mocks the slow wit and lavish clothing of Camillo. Aloud, he asks whether Camillo is going to join Vittoria in bed. Camillo is dismissive and cannot remember when he “last lay” his wife. Camillo confesses to Flaminio that he has his suspicions about Bracciano’s plans. Flaminio puts his brother-in-law’s worries to rest, claiming that Camillo is too wise and lucky to be tricked, but Camillo is not so sure. Flaminio jokes that Camillo should lock up his wife to prevent her from having an affair. Camillo asks Flaminio for advice, but Flaminio insists that free women are “more willingly and more gloriously/chaste” (I.ii.87-88). Camillo, he suggests, is simply being jealous and inventing plots where none exist.

As Vittoria approaches, Flaminio privately promises Camillo that he will convince his sister to sleep with her husband. Speaking to Vittoria, he reveals that her husband is upset. Vittoria defends herself, insisting that she has treated Camillo with respect. Flaminio performatively praises Camillo, and although the man is pleased, Flaminio follows up each compliment with a whispered insult about Camillo in his sister’s ear. Flaminio promises his sister that Camillo will offer her a fantastic jewel if she goes to bed with him. Though Camillo is delighted to hear Flaminio speak, Vittoria understands that her brother is subtly suggesting to her that she go to bed with Bracciano instead. Vittoria urges Flaminio to get rid of Camillo, so Flaminio takes Camillo aside and suggests that he abstain from sleeping with Vittoria tonight, so as to make her desire him all the more on the following night. Camillo is delighted by Flaminio’s advice and tells Vittoria that he will not go to bed with her. He even promises to lock himself in his room. He departs, pleased with what has transpired.

Bracciano emerges from his hiding place and approaches Vittoria seductively. Meanwhile, Zanche lays out a carpet and pillows as a bed for the couple. Cornelia, the mother of Vittoria and Flaminio, enters. She hears what is happening and decries the moral “ruin” of her family, declaring that her daughter’s affair will have disastrous results. Bracciano gifts Vittoria a jewel and tells her to wear it low on her dress. Vittoria speaks about her dream, in which she was confronted by her husband and Isabella, Bracciano’s wife, while sitting beneath a yew tree. They accused her of trying to uproot the tree. Before the pair could bury Vittoria alive, the tree branches were blown violently by the wind and killed them. Flaminio, overhearing this story, believes that Vittoria is subtly hinting to Bracciano that he should kill Isabella and Camillo so that they can be together. Bracciano devotes himself entirely to Vittoria.

As Flaminio takes Zanche from the room, Cornelia enters and chastises the adulterous lovers. She accuses Vittoria and Bracciano of being sinners as Vittoria begs her mother to listen to her explanation. Cornelia says that Bracciano’s wife Isabella is sick and is about to return to Rome. Vittoria insists that the only way she could have avoided the affair would have been through “blood.” Cornelia and Vittoria kneel and pray together for forgiveness. Vittoria leaps up and runs away, ashamed.

Flaminio talks to Bracciano, assuring Bracciano that he knows how to convince his sister to return. Bracciano is not pleased. He blames Cornelia for causing trouble. When he leaves, Flaminio scolds his mother for betraying his plan to improve the family’s financial situation and elevate their social standing. Cornelia is ashamed that she gave birth to a man like Flaminio, who counters that he would have preferred his mother to have been “the common’st courtesan in Rome” (I.ii.323). Upset, Cornelia departs. Flaminio resolves to continue with his plan, using even more deceitful tricks if necessary.