An American couple, Dr. Shane Brown and his wife June, arrive in Paris under the pretense of a romantic honeymoon. However, Shane’s true motive is far darker; he is on a mission to track down the enigmatic neuroscientist Dr. Léo Sémeneau, who once captivated him with his charm, and his wife, Coré. Léo, once a celebrated figure in his field, now leads a covert life as a general practitioner, desperately trying to stay out of the limelight. His desperate measures to protect Coré reveal a disturbing reality: he confines her at home every day, yet her haunting restlessness drives her to escape and engage in violent encounters with unsuspecting men, leading to their grisly deaths.

As Shane delves deeper into the mystery surrounding the Sémeneaus, he learns of their whereabouts from a former colleague of Léo’s, who reveals that Coré is battling severe psychological issues. Meanwhile, two intruders break into the Sémeneau residence, where one discovers Coré in a concealed room. Their encounter quickly turns sinister when she seduces him before inflicting a horrific fate—biting him to death and tearing out his tongue.

When Shane finally arrives at the home, he is met with a shocking sight: Coré, drenched in blood and violence, attempts to attack him. In the ensuing struggle, Shane manages to subdue her, but in a moment of chaos, she accidentally ignites a fire, leaving him no choice but to abandon her to the flames. Just moments later, Léo arrives to witness the devastating aftermath of Shane’s actions and the lifeless body of Coré.

In the wake of Coré’s demise, Shane’s psyche begins to unravel. His relationship with June grows strained; during an intimate moment, he finds himself unable to connect, ultimately resorting to self-pleasure before fleeing. In a disturbing turn of events, he adopts a puppy and returns to their hotel alone. Consumed by his darkest impulses, Shane commits a heinous act against a maid he has been observing throughout the film, brutally raping her and leaving a trail of blood in his wake. Upon washing away his sins, he is met with June’s arrival, and the couple, devoid of true connection, decides to end their trip and return home.