A committed environmentalist whose hyperfixation with everything that's wrong with the world is taking a toll on his marriage tries a pill that reduces human brain capacity from the usual 20% to a mere 2%.

A beautiful American music teacher arrives in Venice and encounters a licentious artist who leads her into the squalid underbelly of the ancient city into a dangerous world of sexual promiscuity. Their experimentation becomes more and more dangerous and our heroine must decide whether to continue down this path or break away before it's too late.

The inmate Proietti, nicknamed "Er Soffia", getting out of prison. There is the Roman brigadier Vasco Sacchetti, an agent of the narcotics and his old friend who, to celebrate his freedom, invites him to eat fish at Fiumicino.