On a flight from Rome to Paris, Georges Chenier, an unemployed man, is accidentally taken hostage by the "Green Standard" movement that believes him to be Julien Tramont, a rich businessman who is caught up in an unhappy marriage despite being a very good father. Just as he was about to leave Rome, Tramont gave up his seat, preferring to spend three days of love, confusion and passion by the sea with Livia, a beautiful Italian woman whom he met the day before...
