Sibling Rivals Death Match
- Cornelia and Marcello are alone. Cornelia asks Marcello if he's going to fight someone, and he says that it's just a rumor (he doesn't say it refers to Flamineo).
- Marcello looks at a crucifix and asks Cornelia if it was the same crucifix, belonging to his father, that Flamineo snapped a limb from when he was a baby.
- Cornelia says it was, but it's fixed now.
- Right then, Flamineo enters and stabs and murders Marcello. Cornelia cries for help. Flamineo yells at her, and says he'll send for a surgeon when he goes to a sanctuary.
- Lodovico, Hortensio, and Gasparo enter.
- As he dies, Marcello tells his mother to remember what Flamineo did to the crucifix. He says he's dying for his family's sins, and the excessive ambition of his siblings. He dies.
- Cornelia denies he's dead, while the others gently try to convince her that he is.
- Brachiano enters, wearing every piece of his armor except the beaver (part of the helmet), along with Flamineo.
- Flamineo admits to Brachiano that he killed Marcello. Cornelia runs at Flamineo with a knife but drops it. She asks God to forgive him and hopes that he lives to repent for such a horrible sin.
- Cornelia helps cover up for Flamineo, not wanting to lose another son—she tells Brachiano that Marcello drew his sword first.
- Brachiano gives Flamineo a lease on his life: he'll need to renew it every day or else be hanged. He also tells everyone not to tell Vittoria about what happened.
- Meanwhile, Lodovico sprinkles poison on Brachiano's beaver.
- The Duke calls for the beaver, and Francisco notes, aside, that he calls for his own death. It's ironic, says Francisco, that the last "good" thing Brachiano did in his horrible life was to pardon a murder.