Onofrio, the Marquis of Grillo, is weary of his aristocratic life. To break free from routine, he conceals his identity and roams the streets of Rome, frequenting its lively inns. One night, he encounters Gasperino, a crude, drunken coal merchant who happens to be his exact double. Onofrio persuades him to trade places—setting off a chain of comic and dramatic misadventures. With sharp wit and rich humor, Monicelli delivers a film layered with social critique, exploring themes of free will, the absurdity of power and privilege, and the human struggle to navigate a chaotic world.