According to my Aurum Encyclopedia of Horror, Dino Risi's Anima Persa can be read as a critique of filmic realism, as an illustration of psychoanalytic processes, or as a political argument, while the entire film is constructed in terms of a process of splitting or 'doubling, making every identity suspect and undermining any sense of emotional and intellectual security.
What is even more baffling than that load of old twaddle is why the film is in the book in the first place: it's not a horror. It's not even a giallo, as some have described it. No-one gets killed. At all. In fact, no-one suffers so much as a stubbed toe. Yes, there's a madman in an attic, but all he stabs with his carving knife is a watermelon. Which might be scary if you're a watermelon, I suppose, but I'm not, and I doubt you are either.
Set in Venice, the film sees teenager Tino (Danilo Mattei) go to stay with his Aunt Sofia (Catherine Deneuve) and Uncle Fabio (Vittorio Gassman) at their sprawling but run-down home. At night, Tino hears strange noises and suspects that someone is living in the attic, which turns out to be true: Fabio keeps his crazed brother Berto there, under lock and key, rather than commit his sibling to an asylum. After this revelation, the plot goes nowhere slowly, with Berto locked in his room, occasionally appearing at the door peephole covered in paint and waggling his tongue.
Tino becomes friendly with Lucia (Anicée Alvina), the pretty life model at his art classes, Uncle Fabio bickers with his wife, and Tino sees his uncle's wild side on a night out on the town. No-one gets killed. In the film's final act, Berto's real identity is revealed and a family secret comes to light. I repeat, no-one is killed.
N. B. Vittorio Gassman actually plays a gas man, Fabio having worked for a Venetian gas company.