This strange, strange Italian movie kind of resembles one of the American low-budget 70's "snakespoitation" films (i.e."Ssss", "Stanley", "Jennifer") but re-imagined as a borderline hardcore porn film (and only available in Italian).
A scientist is sequestered in his villa trying (for reasons that eluded me) to splice together the genes of a snake and himself. His neglected, hot-to-trot wife (Swedish porn star Marina Hedman) meanwhile takes every opportunity to cuckold him with the studly butler (although actually he's more fat than studly--he looks kind of like an Italian Ron Jeremy), or, when he's busy with the maid (African-American porn star--and alleged transsexual--Ajita Wilson), she just uses on her own fingers. After several long (and quite boring) sex scenes, the plot as it were kicks in when the scientist's adolescent daughter (Cinzia DiCarolis) returns from convent school. Her sex-crazed stepmother hits on her (at least, I hope to god she is only her stepmother!), but the girl instead becomes quite, um, enamored with her father's genetically modified snake after it protects her TWICE from being raped. She releases the snake, and it quickly makes short work of the rest of the cast (I'm no herpetologist, but I don't think the same snake could be both a constrictor AND deadly poisonous like this one--but maybe it's the human DNA?)
It's kind of weird seeing Cinzia DiCarolis in a film like this. DiCarolis started out as a child actress in movies like Dario Argento's second film "Cat of Nine Tails", and grew into a kind of slightly more attractive version of Linda Blair. Her most famous role was as a bizarrely dressed nymphet-next-door who tempts John Saxon's character back to his cannibalistic ways in "Cannibal Apocalypse" (and in which she delivers the immortal, dubbed line: "No one has ever bitten me like that before!"). This is no "Cannibal Apocalypse", but DeCarolis, at least, really outdoes herself. She doesn't get as down and dirty as Hedman and Wilson (who briefly share a double-headed dildo in one scene), but she does have naked "sex" scenes with the snake, which may be even more perverted, depending on your point of view. And it's best not to even think of the Freudian implications of a girl falling in love with father's "snake"--believe me, this movie is sleazy enough on a completely literal level.