Constance is a reclusive Parisian music teacher. She gets her jollies by peeking through her window and witnessing the romantic liaisons of her female neighbor. When the girl is strangled by one of her lovers, the killer hides out in Constance's apartment. The widow is turned on by the dangerous eroticism of the situation, and soon becomes the murderer's lover. A blackmailer extracts a great deal of money from the errant Constance, whereupon it is revealed that the "murder victim" is very much alive and part of the extortion scheme ...
