In order to finish his thesis, a shy college student (George Ardisson) starts experimenting with a dangerous drug (I know that's exactly why I experimented with drugs in college). The drug causes him to lose all his societal inhibitions and turn into a full-blown psychopath. He lets his invalid mother die by withholding her medication. He then hooks up with a sexy young woman (Milly D'Abruccio)and they murder her sugar daddy. They then kill a swinging couple and a rich, perverted old lady before they finally resort to poisoning complete strangers. A mad bomber then steals their thunder, so they take brutal revenge on him. At this point the plot changes suddenly and turns into something like "The Secret Life of Walter Mitty" or the end of "The Wizard of Oz", but with much more sex, violence, and erotic jazzer-cizing.
This 1988 film was one of the last gasps of the Italian softcore film industry before they went from interesting sleaze (typified by the "Black Emanuelle" series of Joe D'Amato and Laura Gemser) to much more pedestrian smut (which is about all they make today). It's a very good role for Milly D'Abruccio who went on to become a hardcore porn queen in the 90's and (I assume)probably didn't get to do much acting beyond loudly faking orgasms. She's the only one who doesn't have a dual role in both parts of the movie, and I think she may be meant to represent the dark side of the protagonist. She and another actress (who does the erotic jazzer-cising)have all the nude scenes. But this movie is far more interested in homicidal mayhem and misanthropic sleaze than in generic eroticism, which may annoy some, but, for me at least, it also makes it far more interesting than your usual softcore/sexploitation fare.
This movie does kind of resemble the incredible "Libidine". It's not QUITE as sleazy (and it doesn't have a barely legal girl having weird sex with a snake), but it has the same kind of misanthropic tone and aura of just plain weirdness to it.