[7] The story concerns the Roman dictator Lucio Silla (Lucius Sulla) who lusts after Giunia, the daughter of his enemy Gaius Marius.

Scene 1: A secluded spot on the banks of the Tiber' The exiled Senator Cecilio meets his friend Cinna who tells him his betrothed Giunia mourns his death, a lie by the dictator Silla so that he can win her for himself.

Scene 2 Cecilio excited at the prospect of meeting his betrothed sings of his love (aria: "Il tenero momento").

Scene 3 Cinna restrains Cecilio who has his sword drawn trying to follow Silla, believing he has been instructed by the spirit of Gaius Marius to seek revenge.

She asks Cinna to make sure that Cecilio stays hidden from danger (aria: "Ah se il crudel periglio").

Scene 7 Giunia's hateful face angers him again and he threatens her with death but not to die alone (aria: "D' ogni pieta mi spoglio").

Scene 9 Celia asks Giunia to accept Silla's proposal for the sake of happiness saying she is also to be married to Cinna (aria: "Quando sugl' arsi campi").

Scene 2 Whilst Cecilio accepts his fate Cinna tells him not to worry, Silla's heart over his head will bring about his own downfall (aria: "De' più superbi il core").

Scene 4 Giunia alone with her thoughts of Cecilio's impending death thinks of her own (aria: "Frà I pensier più funesti di morte").

Scene 5: The audience chamber Before the Senators and the people of Rome, to everybody's surprise, Silla declares that he wishes Cecilio to live and marry Giunia.