Years after Marcello has separated from the call girl Laura, he - now married to Anna - hires his ex-lover to give sex education to his jammed son, Sergio. Disgusted by his parents' perverted play, he blocks any attempt by Laura to approach him. Only with great difficulty she succeeds. The two fall in love with each other, but she convinces the boy that it is best for his future life if they part. To prove her love, Laura tears the check Marcello gave her for her services.