(Amadeus). For a long time, Cosi fan tutte was considered scandalous which is not entirely surprising, if you look at its story. After seeing their fiances, Guglielmo and Ferrando, go off to war, two sisters, Fiordiligi and Dorabella, all too rapidly overcome their grief and agree to marry two attractive strangers within the space of just a couple days. Little do the sisters know that the strangers are in fact those same fiances in disguise! The whole thing is a plot masterminded by a cynical old philosopher, Don Alfonso, and a clever maid, Despina. Scandalous or not, Cosi fan tutte has remained one of opera's most contemporary comedies.