An unthinkable betrayal. An unholy sexual alliance. And a vow that must be kept. You never really know a person. Take sweet young Laure. Her husband thought he knew her. He was dead wrong.

Fleeing her abusive husband, SOPHIE found refuge at marquise FOSCARI's home. There, she gets to know HALMEYDA, an Argentinian noble with whom she falls in love. But she is still married. It's then that the marquise suggests a strange deal to her: She takes care of eliminating the troublesome husband, in exchange for which, Sophie must in turn "execute" the marquise's sister who lolls in the most brazen luxury and struggles to destroy her. In fact, one evening, Sophie, hidden in the shadows, attends a totally orgiastic ceremony, that seems to orchestrate a mysterious young masked woman, where sexual practices the most perverse are given free reign. In the morning, the marquise informs Sophie that the "evil husband" has already been sent to meet his maker. It is now that Sophie must fulfill her end of the bargain...