Your Vice Is a Locked Room and Only I Have the Key  (1972)

Theatrical Release Information:
Your Vice Is a Locked Room and Only I Have the Key

A novelist suffering from a bad case of writer's block finds his troubles compounded when the violent murder of his mistress sparks a bloody crime spree in this giallo from The Case of the Scorpion's Tail director Sergio Martino. Oliver (Luigi Pistilli) is an embittered, booze-swilling writer trapped in a loveless, sadomasochistic marriage with his equally venomous wife Irina (Anita Strindberg). Desperate for some physical affection and repulsed by his unaccommodating wife, Oliver schedules an illicit rendezvous with a beautiful young woman who works at a local book store. When Oliver fails to show for their extramarital encounter and later learns that his lover has been slashed to death, a subsequent series of brutal slayings leads him to believe that someone very close to him is harboring a deadly secret. ~ Jason Buchanan, All Movie Guide