In the year 1870 Rome, then governed by the Pope, was captured by the Italian General La Marmora's troops. After the armistice, the Italian soldier Alfonso killed a Pope's soldier, the son of Don Prospero. Then he sought refuge in the house of Don Prospero himself. There Costanza and Olimpia, respectively the wife and the daughter of Don Prospero, fall for him. Then Gustavo, who knew that Alfonso had killed Don Prospero's son arrived in the house... Some things are going to happen.