Rome, 1825. Cornacchia, a Shoemaking, 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. He then goes off to warn his friend Leonida Montanari, a doctor and head of the conspirators, who decides to take out the informer. He and Angelo Targhini, a newcomer from the Duchy of Modena and Reggio, attempt to murder Spada but ultimately fail to deliver the final blow. Spada manages to survive the attack and report his assailants to the police, having them both arrested and subsequently, after a summary judgement, sentenced to death by Cardinal Agostino Rivarola.