In dreary, post-war Britain, Princess Margaret captivates everyone with her cutting-edge fashion sense and biting quips. The royal socialite, cigarette holder in one hand, cocktail in the other, sparkles in the company of her glittering entourage of wealthy young aristocrats known as the Margaret Set, but her outrageous lifestyle conflicts with her place as Queen Elizabeth’s younger sister. Can she be a dutiful princess while still dazzling the world on her own terms?