Ferrando and Guglielmo are convinced that their girlfriends Dorabella and Fiordiligi would never be unfaithful. Their friend Don Alfonso doubts this and persuades the men to try an experiment. Ferrando and Guglielmo must pretend to have been called away to war; they will then return in disguise and attempt to seduce their former girlfriends. If they don't succeed within 24 hours, Alfonso will pay them a large sum of money. To begin with, all appears to go well: Fiordiligi and Dorabella spurn their 'suitors' and the men eagerly anticipate their winnings. But as Alfonso and his assistant Despina step up the pressure and the men try to woo each other's girlfriend, things get more complicated. Are the girls as loyal as the men thought? Are any of them the people they thought they were?