Approaching 40, Emilio (Anthony Franciosa), has lived among ideas and books, and is looking for a short-term relationship with no responsibilities. He seeks to emulate his friend Stefano (a successful womanizer) (Philippe Leroy) and tales of adventure that he has read about in books, but not experienced.
He meets the younger Angiolina (Claudia Cardinale), a beautiful and vivacious lady, whom he perceives as free and innocent. He will educate her in the ways of the world and reduce her naivety.
He happily tells his sister, Amalia (Betsy Blair), with whom he lives, of the encounter. She tells him not to do anything stupid, and asks if the lady is honest.
A work colleague drops hints that Angiolina may not be quite the "little angel" that her name suggests. Photos in her home also suggest that she has known a number of men previously. Progressive observations of Angiolina, around Trieste, reveal her with multiple men.
During a trip to a restaurant, Angiolina also develops an instant rapport with Stefano, and he persuades her to pose for him ("dressed") in his work as a sculptor.
Meanwhile, his sister Amalia develops an infatuation with the talented Stefano. When Emilio stops Stefano from seeing her any more, it leads to tragic consequences…