At the execution grounds in the palace of the Viceroy of Portugal, the viceroy laments the “death” of Balthazar. Viluppo reaffirms Alexandro’s treachery. Alexandro is brought out to be executed. Alexandro asserts his innocence, but the viceroy orders him to be tied to a stake to be burned. Alexandro warns Viluppo that he will face vengeance for this betrayal. Viluppo feigns outrage and threatens to kill Alexandro. 

The ambassador arrives just in time, declaring that Balthazar is alive and safe. He gives the viceroy letters from the Spanish King. Outraged, the viceroy stays the execution. Alexandro asks how he wronged Viluppo. Viluppo admits that he turned on Alexandro, hoping to profit from his death. The viceroy promises to invent new, extreme forms of torture to punish Viluppo. Alexandro tries to ask for mercy for Viluppo, but the viceroy ignores him. The viceroy will honor Alexandro for his loyalty. They leave to have a council over the letters from Spain.

Outside Cyprian’s palace, Hieronimo laments Horatio’s death. He questions the justice of the heavens if Horatio goes unavenged. He wanders, distracted, driven by the desire for revenge as though goaded on by demons.