An acid portrait of Italian youth at the time, I DELFINI follows a dreary season of discontent and viciousness in the lives of a thoroughly unpleasant group of mostly rich youngsters in a small Adriatic coast city.

Young "Paolo" is an orphan who falls in love with the charming singer "Marisa". She hope that he will fund her new magazine, but when she discovers he has already spent all his money on her, she rejects him. Desperate, he does something of which he will soon be ashamed.

Rome, 1527. Massimo Colonna is in love with Angela, a member of the Orsinis, the Colonnas'arch enemies. As she is officially engaged to Tancredi Serra, the latter, a faithless individual, has Massimo accused of the murder of Prince Orsini whereas he himself has woven it. Massimo is rejected by an outraged Angela and banned from Rome.Meanwhile the Eternal City has to face a brutal attack by armed invaders from Spain. The Spaniards are about to storm Rome when Massimo and his troops appear. The invading forces are defeated and Massimo is acclaimed by the crowd. After clearing his name, he can marry Angela.