Diana Dixon, a Texan girl (played by Dors), wins a quiz show jackpot, and uses her winnings (a prize in cash and a brand new Cadillac car) for a trip to Italy. Her car breaks up near Siena where she meets Prince Piero di Montalcino (Gassman), a handsome Italian nobleman. He believes that she must be rich, and she also thinks that he must be wealthy, but that's very far from the truth.
The romance reaches its climax at the traditional Palio horse race where, after Diana breaks up with the prince upon hearing that he bribed the jockey of the rival contrada into throwing the race so that his horse could win, she fast-talks the rival horse's owner into letting her ride. After winning the Palio, she will accept to marry the Prince.
Diana Dors - Diana Dixon
Vittorio Gassman - Piero di Montalcino
Franca Valeri - Contessa Bernardi
Bruce Cabot - Mike
Teresa Pellati - Laura
Tina Lattanzi - Madre di Piero
Enrico Viarisio - Il zio di Piero
Nando Bruno - Papà ferrari
Ronaldo Bonacchi - Tino
Many of the extras for the horse race scenes were real jockeys, some of which quite known to the Sienese. One of them, Pietro De Angelis (nicknamed "Pietrino"), winner of two previous Palio races, died of a heart attack while the movie was being filmed.
The movie was also a springboard for the career of the sole woman jockey of the modern Palio horse race, Rosanna Bonelli, nicknamed "Diavola" but better known as "Rompicollo" ("breakneck") from the name of an operetta written by her father. She raced first in a mock Palio race staged for the shooting crew, in place of the jockey of the "Pantera" team (unbeknownst to the film production) and then as a stuntwoman for Ms. Dors in the victory scenes, riding the mare Gaudenzia. That helped the girl's rise to local fame and to crown her dream to run in the real Palio race of August 16, 1957 racing for the "Aquila" team, her first and last race on Siena's scenic Piazza del Campo, and although she didn't finish in first place like the film's heroine, she was bestowed the title of "honorary jockey" by the "contrada".