This adventure/spy/romance story is set during the French Revolution as a notorious Englishman has taken upon himself the rescue of French aristocrats, whom he smuggles into England. Many of these aristocrats are taken from the city of Paris and the smuggler leaves behind a red star-shaped flower called a scarlet pimpernel by English speakers. Thus, he becomes known as the Scarlet Pimpernel. (Paris is mentioned later in the novel, too.) But, not until the end of the novel is Sir Percy's identity revealed.
In Chapter 2, the narrative moves to a small inn known as Fisherman's Rest in Dover, England, on the English coast. Later, in Chapter 9, Antony informs Andrew about his plan to meet a man named Hastings, in Calais, France. Just as Dover is on the English side of the Channel, Calais is on the French side of the English Channel. In Chapter 12, London, England is mentioned. In Chapter 23, Calais, France, is again mentioned and the Chat Gris Inn there.