In 19th century Europe, nobleman Kurt Menliff returns to his family's seaside castle after many years of absence in order to supposedly congratulate his younger brother Christian for marrying his former lover Nevenka. However, those at the castle know that Kurt is a sadist and are unhappy with his presence, especially his father Count Menliff and housemaid Giorgia, the latter of whom blames Kurt for the suicide of her daughter Tania, with whom Kurt had an affair before abruptly abandoning her. Nevertheless, they decide to let Kurt stay at the castle overnight.
The next day, [Kurt] finds [Nevenka] sitting by herself on the beach. After seducing her, they kiss, but Nevenka suddenly backs away in a panic and strikes Kurt with a riding crop. In response, Kurt takes the crop and whips her on the back several times, to which Nevenka apparently reacts with sexual excitement as she and Kurt make love immediately afterwards. In the evening, after Nevenka fails to return to the castle, [Christian] sets out to look for her alongside butler [Losat] and [Katia], whom is secretly in love with [Christian].
Meanwhile, an unseen figure stabs Kurt in the throat with the dagger that Tania used to kill herself. [Losat] finds Nevenka lying unconscious on the beach, and he and the others take her back to the castle and put her to bed before discovering Kurt's body.
After Kurt's funeral, the relationships between Nevenka, [Christian] and [Count Menliff] begin to fall apart, as [Christian] suspects his father of having killed Kurt, and Nevenka overhears [Christian] declaring his love for [Katia]. Nevenka also begins seeing Kurt in numerous ghostly visions, including one in which he whips her several times in her bedroom, leaving welts all over her body. Eventually, [Count Menliff] is found dead in his bedroom, having been killed in the exact same way as Kurt.
As the castle occupants start to suspect each other of killing the Count, Nevenka suddenly disappears from the castle and is found in the family crypt in an apparent state of ecstasy, claiming that Kurt carried her to the crypt and whipped her. As [Christian], [Katia] and [Losat] also start having supposed visions of Kurt, [Christian] comes to believe Nevenka's claims that Kurt's ghost is the one behind the Count's murder, so he and [Losat] decide to unearth and cremate Kurt's body in an effort to bring an end to the hauntings.
While burning the body, Christian and [Losat] hear a sinister laugh and spot a figure in a cloak spying on them. Christian chases after the figure, who is revealed to be a crazed Nevenka, who attempts to stab Christian with the dagger before fleeing back into the crypt. There, she has another vision of Kurt, and attempts to stab him, but inadvertedly stabs herself, much to Christian's dismay. Before dying, she reveals to Christian that she has "killed Kurt again, this time for good." Losat and Christian determine that Nevenka had gone insane or was perhaps possessed after murdering Kurt, leading her to kill the Count and stage the various hauntings. Meanwhile, as Kurt's body continues to burn, a riding crop placed in his coffin appears to move by itself.
