The screenplay by Nicola Guaglianone explores in depth the feelings of the twins nearing the age of 18 and the differences in their personalities. They have grown up in poverty in a town outside Naples, with a father, Peppe (Massimiliano Rossi), who from their birth viewed them as his ticket to survival. Their mother is subjugated and has gone along with her dictatorial husband, who gambles away money earned by the twins singing songs he composes at local social and religious events.

Angela and Marianna Fontana are wonderfully effective as Viola and Daisy, and they portray the twins perceptively, both in illuminating their being tied together and the different feelings that develop. Daisy has greater aspirations than her sister and dreams of a life of sexual expression and personal achievement. Viola is more content to adore her sister and maintain their emotional bond. When they meet a doctor who says it would not be a problem to safely separate them in surgery, given their being co-joined at the hip and not involving basic organs, Daisy is taken with the idea, but Viola is fearful of life apart.

The situation is compounded when Daisy sets her eyes on a glib-talking entertainment agent (Gaetano Bruno), who promises to help her and her sister. To an audience it is clear he is a dangerous phony. The father of the twins forbids them to undergo surgery—that would end his opportunistic ability to exploit the girls. Although the doctor has offered to perform the surgery without a fee, the twins need to raise money for the hospital costs and the trip to Switzerland for the operation.

There is a poignant section of the film in which they secretively leave home and attempt to get to their destination, with Daisy under the illusion that they can get no-strings money from the supposed benefactor aboard his yacht. We sympathize with her, fully expecting that no good will come of the expedition. What happens when they reach the yacht justifies our fear.