London society buzzed with one name that spring: Miss Edgeworth.

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The year was 1813. The Regency era was in full swing, and the upper class had assembled for the season in a pastel whirl of lace and silk, complete with calling cards and exclusive dinner parties. The Napoleonic Wars raged across continental Europe, but that did not stop society life from carrying on in all its dazzling elegance.

George III sat on the throne; Queen Charlotte presided over her court. A burst of interest in antiquity had inspired the stylish ladies of Mayfair and Marylebone to dress themselves like modern Cleopatras and Helens, with high waists and flowing skirts. Fashionable gatherings were peppered with the prose of neoclassical writers and Romantic poets.

Yet amid all the decadent breakfasts and sparkling balls, one socialite found herself on a deeper mission as the days grew longer and a warm summer set in.…