Julian (Jean-Pierre Leaud) is the son of German industrialist Klotz (Alberto Lionello) who seeks to go into business with the former Nazi Herdhitze (Ugo Tognazzi). Herdhitze had spent most of World War II collecting human skulls for experiments with brain matter.
As a protest, Julian refuses to marry his fiancé from a pre-arranged marriage, and he becomes romantically involved with pigs. Part two finds a man driven to cannibalism by hunger while wandering Mount Etna. He scavenges the mountainside looking for any kind of sustenance.
In both cases, humans revert to animal behavior when they are removed from the spectrum of social rules and opinions.