Sir Percy is a wealthy English baronet who rescues individuals sentenced to death by the guillotine. He soon reveals himself to be a master of disguise, an imaginative planner, a formidable swordsman and a quick-thinking escape artist. With each rescue he taunts his enemies by leaving behind a card showing a small flower—a scarlet pimpernel. The identity of the Scarlet Pimpernel thus becomes a topic of widespread popular interest and the hero himself becomes the subject of an international manhunt by the French revolutionary authorities. To hide his true identity, Sir Percy presents himself in everyday life as a dim-witted, foppish playboy. His secret is kept by a band of friends known as the League of the Scarlet Pimpernel. The league operates as an undercover team in enacting Sir Percy's rescue plans.
Orczy's general sympathy with aristocrats is evident in her stories, where nobility of birth and nobility of character easily correspond. Even so, her tales present commoners as capable of selfless and heroic actions. Marguerite St. Just and her brother Armand, both commoners who initially help bring about the French Revolution, work closely with Sir Percy as members of the League.