Sir Duke
- The Duke of Brachiano arrives at the residence of Vittoria Corombona and her husband, Camillo.
- He complains to Vittoria's brother, Flamineo (who works for the Duke), telling him that he's hopelessly in love with Vittoria.
Flamineo assures the Duke that Vittoria's into him too. Flamineo and Vittoria's maid, Zanche, will arrange a meeting for them late at night. - He also tells the Duke that women like Vittoria aren't really shy or scared of seduction—they're just acting like it to enflame the desires of their suitors.
- When Brachiano worries about Vittoria's husband, Flamineo tells him that Camillo is just a wimp who can't please a woman. He also tells him that he shouldn't be overly hot to get with Vittoria—men who are in marriage always want to get out of it, even though others want to get in.
- Camillo approaches, as Flamineo finishes mocking him (Camillo doesn't hear). Brachiano exits.
Silkworm Sex Machine
- Flamineo chats with Camillo about his marriage, and Camillo admits his been preoccupied with voyaging (he fights pirates for a living) and doesn't remember when he last slept with her. He says he always wakes up with a "flaw" (space) between him and Vittoria whenever they do have sex.
- Camillo admits that he knows Brachiano is trying to seduce his wife. Flamineo tries to convince him differently, reminding him of his favorable horoscope, but Camillo's not buying it.
- Flamineo pretends to advise him in favor of locking up his wife. Camillo thinks this is good advice, but Flamineo reveals he was kidding—that's a sure way to get cuckolded, regardless of your wife's chastity. He should let Vittoria remain at liberty.
- None of Flamineo's jokes about cuckoldry make Camillo less anxious, though. Flamineo tries to tell him that his jealousy is like a pair of glasses that are designed to distort appearances—you see adultery everywhere.
- Vittoria enters. Flamineo tells her she should be nicer to Camillo and accept his entreaties—while constantly mocking him in asides to the audience. He talks Camillo up, saying that he'll lie with Vittoria in an extremely luxurious bed and give her the philosopher's stone and so on.
- But, craftily, Flamineo tells Camillo not to sleep with Vittoria tonight—he needs to make her wait, so she'll be more eager.
Camillo agrees, and tells Vittoria he needs to wait a night, like a silkworm, to spin a finer thread. He thinks this is a witty remark, and leaves. - The maid, Zanche, prepares the cushions for Vittoria's midnight rendezvous with Brachiano. Brachiano arrives and confesses his love to Vittoria—she seems very receptive. But, all the while, Vittoria and Flamineo's mother, Cornelia, is listening in.
- Vittoria and Brachiano talk about exchanging jewels, in a somewhat sexually charged moment.
- Then, Vittoria tells Brachiano about a dream she had: in the dream, she's crying under a yew tree in a cemetery. Her husband, Camillo, and the Duke's wife, Isabella, come along and accuse her of trying to uproot the yew tree and replace it with an evil blackthorn.
- They try to bury her alive, but a whirlwind comes along and knocks over the yew, killing them and burying them in the grave they've been digging.
- Flamineo remarks aside that Vittoria is suggesting to the Duke that he murder her husband and his wife, in a veiled way.
The Duke promises to "protect" Vittoria from them, and promises that she'll be everything to him.
Parental Supervision
- Cornelia steps into view and angrily accuses Vittoria and the Duke of adultery. (Zanche exits).
- Vittoria plays innocent, and the Duke tries to speak, but Cornelia condemns the Duke for setting a terrible example, and curses her daughter—wishing her a short life if she betrays her husband.
- Vittoria feels cursed and exits.
- Brachiano, angry with Cornelia, leaves—but tells Flamineo to send Doctor Julio (a poison expert) to him.
- Flamineo complains about how Cornelia (his mom) interrupted his boss, the Duke—which reflects badly on Flamineo.
- Cornelia says that just because they're poor doesn't mean they need to be vicious—deceitful and murderous. Flamineo says he's just trying to get rich, to add to the (apparently small) fortune his dead father left him, and doesn't need any of her moral qualms. He's made of tougher stuff.
- Cornelia wishes she'd never given birth to him, and Flamineo wishes he'd had a prostitute for a mother so he would've had multiple presumed dads to take care of him. He tells her to go tell the cardinal (Camillo's uncle) about what's going on if she feels so bad. Cornelia exits.
- Alone, Flamineo complains that the duchess (Brachiano's wife, Isabella) has come to court. But, he says, they need to continue their mischief—using the twisting manipulations of a snake, they'll eventually get what they want.