She is best known for her series of novels featuring the Scarlet Pimpernel, the alter ego of Sir Percy Blakeney, a wealthy English fop who turns into a quick-thinking escape artist in order to save French aristocrats from "Madame Guillotine" during the French Revolution, establishing the "hero with a secret identity" in popular culture.

Finally, in 1880, the 14-year-old Emma and her family moved to London, England where they lodged with their countryman, Francis Pichler, at 162 Great Portland Street.

Although not destined to be a painter, it was at art school that she met a young illustrator named Henry George Montagu MacLean Barstow, the son of an English clergyman; they were married at St Marylebone parish church on 7 November 1894.

While the couple waited for the decisions of these publishers, Fred Terry and Julia Neilson accepted the play for production in London's West End.

[9] Introducing the notion of a "hero with a secret identity" into popular culture, the Scarlet Pimpernel exhibits characteristics that would become standard superhero conventions, including the penchant for disguise, use of a signature weapon (sword), ability to out-think and outwit his adversaries, and a calling card (he leaves behind a scarlet pimpernel at each of his interventions).

[1] By drawing attention to his alter ego, Blakeney hides behind his public face as a slow-thinking, foppish playboy, and he also establishes a network of supporters, The League of the Scarlet Pimpernel, who aid his endeavours.

[1][10] Orczy went on to write over a dozen sequels featuring Sir Percy Blakeney, his family, and the other members of the League of the Scarlet Pimpernel, of which the first, I Will Repay (1906), was the most popular.

Other popular detective stories featured The Old Man in the Corner, a sleuth who chiefly used logic to solve crimes.

[11] In The Nest of the Sparrowhawk (1909), for example, a malicious guardian in Puritan Kent tricks his beautiful, wealthy young ward into marrying him by disguising himself as an exiled French prince.

He persuades his widowed sister-in-law to abet him in this plot, in which she unwittingly disgraces one of her long-lost sons and finds the other murdered by the villain.

[15] Orczy's work was so successful that she was able to buy a house in Monte Carlo: "Villa Bijou" at 19 Avenue de la Costa (since demolished), which is where she spent World War II.