sienna cathedral. the siennese return victorious. cordelia, frightened by her brother's threats has taken refuge in the cathedral. giugurta find her there having extracted the information before killing uberta. after proud protests, cordelia faints on the altar steps, and he takes advantage to make her swallow poison. the victors come in with orso at their head. cordelia has convulsions which are mistaken for the plague. the crowd disperses in horror, and orso takes cordelia in his arms. so doing, he condemns himself to be trapped with her in the place tainted by the plague. at their pleas, azollino joins them in marriage. alone, they exchange parting words : orso's wound has re-opened, and the two lovers die side by side.