Your Vice Is a Locked Room and Only I Have the Key

Your Vice Is a Locked Room and Only I Have the Key (Il tuo vizio è una stanza chiusa e solo io ne ho la chiave) is a 1972 giallo film directed by Sergio Martino. The picture stars Edwige Fenech, Luigi Pistilli, and Anita Strindberg. The film revolves around a depraved writer and his mistreated wife, whose fragile relationship is complicated further after several murders occur nearby, while the author's beautiful niece suddenly comes to visit.

Your Vice Is a Locked Room and Only I Have the Key was Martino's fourth giallo film. The film uses many elements from Edgar Allan Poe's 1843 short story "The Black Cat" and acknowledges this influence in the film's opening credits. The title of the film is a reference to Martino's first one, The Strange Vice of Mrs. Wardh (Lo strano vizio della Signora Wardh, 1971), in which the killer leaves the phrase as a note to his victim. The victim in that film was played by Fenech. The film has been released under several alternate titles, including Gently Before She Dies, Eye of the Black Cat and Excite Me!.

Plot
Oliviero Rouvigny, a washed-up writer and alcoholic, lives in a crumbling mansion where he abuses his wife Irina and their maid Brenda and holds decadent parties for local hippies. Irina is scared of Satan, the cat of Oliviero’s late mother Esther, a former actress. Oliviero is protective over his mother's dress from when she portrayed Mary Stuart.

After his mistress Fausta is found dead, Oliviero is investigated by Inspector Farla after being identified by Fausta's boss Bartello. Oliviero lies to the police that he was home, with Irina covering for him, despite her suspicions. At night, Brenda puts on Esther's gown and is silently watched by Oliviero. Brenda is attacked by someone with a bill-hook, and she dies after Irina discovers her. In fear of being labeled the killer after being earlier suspected for Fausta's death, Oliviero convinces Irina to bury Brenda in the cellar and forces her to wash his mother's gown.

Oliviero's niece Floriana suddenly visits from Paris, while a gray-haired man also appears to spy on the Rouvignys. While Floriana is kind towards Irina, it becomes obvious to them that Oliviero is attracted to his now grown-up niece. The gray-haired man shows up and gives Irina Esther's gown that has been dry-cleaned, enraging Oliviero who locks Irina in the closet, where she is clawed by Satan. Oliviero visits Floriana, who mocks him with his attraction to her and his rumors that he had an incestuous affair with his own mother. Floriana later finds Irina in the closet and frees her, and the two start an affair.

The killer murders prostitute Giovanna, whose aunt kills the attacker; the killer was Bartello, who was an escaped mental patient faking a new identity. Floriana begins dating milkman and aspiring motorbike racer Dario. After being forced to drop out of a race, Dario has sex with Floriana in an old barn where Oliviero spies on them. Irina catches Satan after the cat kills several of her pet doves, and she stabs one of its eyes out with scissors. Local junk woman Mrs. Molinar witnesses this and Irina drives her off.

Oliviero finds Floriana laying in bed wearing his mother's gown. Floriana reveals she knew that her uncle spied on her when she slept with Dario in the barn and then proceeds to seduce him. Oliviero becomes more violent towards Irina, and Irina and Floriana plot on how to take him out.

One night, Irina discovers her husband in bed with Floriana and overhears Oliviero's plan to murder her and place her body in the cellar so he could be with his niece as his lover, but Oliviero finds and beats her. Dario secretly talks with Floriana, asking her to meet him in the morning so they can go to a race for a lucrative contract. Irina sees Satan and chases him into the cellar where she discovers that Brenda's corpse has been uncovered, giving credence to Oliviero's plan.

Irina approaches Olivero, passed out next to his typewriter, and sees that he has finally made progress by typing out his murderous fantasies. She violently stabs him to death with the scissors. Floriana witnesses the murder and helps her hide Oliviero's body in the cellar. Floriana reveals that she had visited them to retrieve Esther's jewelry that Oliviero possessed, since it would be passed on to her now that her grandmother and uncle are dead. Irina gives her the jewelry and the two have sex one final time. Someone sneaks into the house and begins writing "vendetta" repeatedly on Oliviero's typewriter before escaping as Irina and Floriana investigate. Disturbed by these events, Floriana abandons Irina and flees to meet Dario.

The gray-haired man, Walter, appears and meets with Irina, who is revealed as the mastermind all along and is his lover. Irina killed Esther and had Brenda killed by Walter. Her original plan was to drive Oliviero mad thinking he killed Brenda, however his own plans to kill her forced her hand. In the highway, Walter causes an oil spill that results in Dario and Floriana having a fatal accident, enabling Walter to retrieve the jewels. Irina later pushes Walter off a cliff to have them all for herself. She returns to the mansion to find Farla there, since Mrs. Molinar had filed a complaint to the police after Irina injured Satan. Inside, they hear Satan's meowing from the cellar, where the police uncover Oliviero's body and Satan, to Irina's agony.

Cast

 * Edwige Fenech as Floriana
 * Anita Strindberg as Irina Rouvigny
 * Luigi Pistilli as Oliviero Rouvigny
 * Riccardo Salvino as Dario
 * Ivan Rassimov as Walter
 * Angela La Vorgna as Brenda
 * Enrica Bonaccorti as Giovanna
 * Daniela Giordano as Fausta
 * Franco Nebbia as Inspector Farla
 * Ermelinda De Felice as Madam
 * Marco Mariani as Bartello
 * Nerina Montagnani as Molinar
 * Carla Mancini
 * Bruno Boschetti as Vittorio
 * Dalila Di Lazzaro as Stripper (uncredited)