France and England, September 1792. A secret league of English gentlemen removes aristocrats from revolutionary France under the direction of an unknown leader who signs his messages with a small scarlet flower. In London, Sir Percy Blakeney appears to be a wealthy and empty-headed fashion leader, while his French wife Marguerite remains estranged from him after a denunciation in her past contributed to the death of an aristocratic family.
The French agent Chauvelin coerces Marguerite into helping identify the Pimpernel by threatening her brother Armand. When she discovers that the man Chauvelin is hunting is Percy himself, she follows the pursuit to Calais and attempts to repair the trust between them. The novel sets its rescue adventure against the September Massacres and the radicalisation of the Revolution, establishing disguise, divided loyalty and marital reconciliation as the central patterns of the series.