Libidine (1979)

Prof. Gianni, a scientist, sequestered in his villa wants to transplant the metabolism of the snakes into the human body. His neglected wife Carla meanwhile takes every opportunity to cuckold him with the butler when he is in the laboratory . Meanwhile his adolescent daughter Anna returns from convent school. Her sex-crazed step-mother hits on her, but the girl instead becomes quite enamored with her father's genetically modified snake after it protects her twice from being raped.