In Rome in 1825, Cornacchia, a shoemaker, finds out that prince Filippo Spada, a Carbonari associate, is going to reveal the organization's plans for an uprising to the Pontifical Guard's commander, Colonel Nardoni.

Spada manages to survive the attack and reports his assailants to the police, who have them both arrested and, after a summary judgement, sentenced to death by Cardinal Rivarola.

The shoemaker, with his disciple Bellachioma, writes a poem in which he asks to hurry the execution of the two Carbonari and explains to his pupil that only their deaths may lead the people to consciousness.

In the meantime, people from the streets assault Castel Sant'Angelo, which leads Montanari to believe that they will revolt and set them free, but he soon learns that even his fellow citizens want them dead.

In the end, Targhini is decapitated and Montanari, before being executed as well, takes one last gaze upon the citizens of Rome gathered in Piazza del Popolo and says, "Good night, people."