High-spirited Thalia Horrocks, desperate to escape from the restrictions of the conventional middle-class life she lives and the loathsome suitor her stepfather and mother have chosen for her, decides to write a novel on a most scandalous subject.She prevails upon her fast cousin, Lynton, to introduce her to the pretty horsebreakers, the courtesans who flaunt their wares in Hyde Park every afternoon. Unexpected complications ensue as Lynton takes Thalia to the notorious Cremorne Gardens and introduces her to the eccentric, Lady Guenevere Shallot, a courtesan who changes her name to suit the decor of her home in St. John’s Wood. Thalia’s curiosity gets her into serious trouble, including trapped in a brothel that peddles young girls to jaded noblemen, but her courage, her generous heart and her new friends help her escape from a desperate situation, discover her true identity and find true love.