(While Oscar Wilde was imprisoned in Reading Gaol, his manuscripts were stolen from his villa; among them was A Florentine Tragedy, not yet published. After his death, the manuscript was discovered but without the first scene of the drama. Zemlinsky composed his opera to the direct German translation by Max Meyerfeld, making only a few cuts.)

The merchant Simone, returning home from a trading journey, finds his wife, Bianca, in a compromising situation with Guido Bardi, the son of the Duke of Florence. Simone, who in rank, outward appearance and education is inferior to the young aristocrat, at first attempts to minimize an embarrassing situation through small talk, not daring to allow his jealousy to surface. But neither bargaining over his wares, which he forces on the young Prince, nor political discussions ease the smoldering tension. The Prince, through candid insinuations regarding his relationship to Bianca, provokes her husband to such an extent that an altercation becomes unavoidable. “Is the whole, mighty world limited to the confines of this room and does it have only three living souls as its inhabitants? So let this humble room now be a world-stage, where rules fall and our passive lives are the stakes for which God plays.” Simone, driven to the ultimate, challenges his rival to a duel and kills him. As if transfigured by the “great deed,” his wife sinks into his arms, and they confess their mutual love.