Tranquil America of the early twentieth century is the setting for Joe D'Amato's (billed here under his real name, Aristide Massaccesi) first plunge into the sex and horror genre, in which he would go on to be somewhat of a pioneer. The film opens with a mournful man by the name of Frans doting over his sister Greta's lifeless corpse. Caressing her enticing frame, a flood of memories overcomes him as he recalls the many warm experiences he had with her. However, his composure soon turns vengeful, as he recalls her last days and the hands at which her fate was sealed. The film truly begins with an elongated flashback playing out in Frans' mind, where Greta, her horse carriage taking a nasty spill and leaving her unconscious, soon becomes at the mercy of the nearby neighbors. She is soon laid up in bed and examined by a mysterious physician, Dr. Sturges (Klaus Kinski) and diagnosed with amnesia. Stripped of her memory, Greta recuperates in the Good Samaritans' household and eventually befriends her caretakers and becomes an integral part of their elitist society. In addition, she manages to win the hearts of a married couple, Walter and Eva. Not only does Greta break their marital vows, but a strange chain of murders begins to crop up around the mysterious guest as she continues her stay. The explanation to such mysteries includes no more than supernatural revenge, medical science that can bring back the dead, and many hallucinatory twists and turns challenging the coherency of the tale's fabric.