Rosanna Schiaffino, Gian Maria Volonte and Richard Johnson star in one of my favourite Italian films to come out of the 60's. Ivan Rassimov even makes an appearance in one of his earliest roles.
I wouldn't usually quote straight from the imdb but I found this the best way to put across the basic plot of the film without totally spoiling it, I tried to write something myself but kept stumbling...
"Sergio (Johnson) has noticed an old woman (Consuela, played by Sarah Ferrati) who seems to be around him and near all the time and is quite surprised to learn that it was she who placed an ad in the local newspaper for somebody to chronicle her deceased husband's papers, which are quite erotic in nature. Sergio has doubts about this but accepts the job when he meets Consuela's' beautiful daughter Aura, ably portrayed by Rosanna Schiaffino, a dark-haired beauty who reminds somewhat of the great Italian horror actress Barbara Steele. The remainder of the story is the three-sided psychological duel between Aura, Consuela and Sergio. Sergio, very much a man of the world, surrenders his soul and self respect when he murders Aura's current lover in order to win the right to stay in the old woman's house to be near Aura. Only, the old woman has other plans, for she is a witch and can force Aura to come and go at will. For all practical purposes Consuela and Aura are one and the same person, and Consuela has been enamored of the handsome Sergio for a long time"
