Comte Paul de Valreas is attracted to Frou Frou, the frivolous wife of Henri de Sartorys and the indifferent mother of their young son Georges. Paul persuades Frou Frou to bring her somber sister Louise, who secretly loves Henri, into the household, thus freeing her from any domestic duties. Frou Frou returns Paul's affections and neglects her husband and son even more than before. Louise quickly assumes direction of Henri's home and innocently supplants Frou Frou in the eyes of her husband and child. Sensing that her presence is no longer needed at the Sartorys estate, Frou Frou bitterly denounces Louise and then elopes with Paul to Venice. Henri pursues them and slays his rival in a duel. Alone in Venice, Frou Frou becomes gravely ill. She is found on her deathbed by Louise, who summons Henri and Georges. As she dies, Frou Frou gives the three her blessing.