Isabella, the daughter of Olivo, a merchant of Lisbon loves Camillo, a shop assistant. Her father wants her to marry Le Bross, a wealthy trader from Cadiz.

When Le Bross arrives, Isabella confesses that she loves another but she pretends that her beloved is a vain old fellow, Columella. Discovering that Isabella is intent on disobeying him, Olivo becomes enraged. Seeing the girl's despair, Le Bross gallantly offers to help her win her heart’s desire.

Following his plan, Isabella and Camillo threaten to kill themselves. They hurry out, whereupon shots are heard from off-stage. Olivo's tender-hearted brother Pasquale is filled with remorse. When Isabella and Camillo re-enter wreathed in smiles, Olivo gives them his blessing.