An Italian adaptation of the Richard Wagner opera Lohengrin, where a woman prays for a saviour, and receives it in the form of the title character, a man who will marry her and stay by her if she never asks him his name.

A young student of an upper-class background who is surrounded by classmates that are of working-class backgrounds, after a novel in diary format by Enrico Bottini.

The monotonous life of a bourgeois family is disturbed by the announcement of the imminent return from America of Mr. Lohengrin, who had left Italy years earlier, leaving behind the reputation of being an irresistible womanizer. Lohengrin's cousin, worried about the stability of his marriage, convinces some relatives who live in the countryside to welcome the dreaded guest into their home and then, to avoid meeting him, leaves. Meanwhile, in the country house everyone eagerly awaits Lohengrin, and envy and spite are unleashed during the wait. In particular, while the young landlady prepares the house, the woman's husband begins to be tormented by jealousy. But the arrival of the long-awaited guest will be a huge disappointment for everyone: the once seductive man is now just an aged, with glasses and a prominent belly.