A young wife, Jan has a mental breakdown and spends time in a hospital. Eventually, she wants to go home, but her doctor is hesitant to release her. Still the woman, wanting to save her disintegrating marriage, insists. Upon her return, she and her archaeologist husband, Greg are visited by Laura, his seductive "sister." The poor wife is appalled by the too close relationship between the two and shares her discomfort with her landlord and he has a peculiar reaction. Meanwhile, the hapless wife seems to becoming increasingly paranoid and strange. She has no idea that drugs are behind her odd behavior. Eventually, she goes over the edge and shoots her sister-in-law, and still the madness continues until the story's violent climax.