Lake Maggiore provides a beautiful and evocative backdrop to the action: the central events of the film take place around Baveno as opposed to Oggebbio in the novel.

After spending World War II in neutral Switzerland to avoid military service, an unsure young man named Marco arrives in his boat on Lake Maggiore.

He is befriended by a quirky man named Mario, a womanising liar who, after a colourful life as an army officer in Africa, has married Cleofe Berlusconi, a rich older woman who resents his laziness and his weakness of character.

Mario cultivates Marco as an escape from his stifling home life and joins him on his boat for a cruise with two uninhibited Swiss girls.

When a fierce storm hits the lake, they all take refuge in a hotel and, stepping out for some fresh air after dark, Marco sees a man on a bicycle who looks just like Mario.