In the eighteenth-century Rome, Don Pasquale Corneto, wants his young nephew Ernesto, dedicated to a wasteful social life, to marry a rich spinster, both to save on the expenses of his maintenance and to increase the family heritage.

During the Spanish occupation of Naples, the people led by Tommaso Aniello - known as "Masaniello" - plot against the Viceroy. The Viceroy's son, under another name, has a son from Masaniello's sister, but his father has already planned a marriage for him with a Spanish patrician against his wishes.