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

A burned out, abusive, alcoholic writer named Oliviero lives with his wife, Irina, at their estate in Venice, along with his late mother's mysterious black cat, Satan. To pass the time, Oliviero hosts parties for the local hippies, humiliating Irina in front of his guests. When his mistress is murdered, police suspect Oliviero, and things get complicated when his young, beautiful and self-confident niece, Floriana, pays an unexpected visit.