In 1826 London, two brilliant girls form an unlikely detective partnership. Eleven-year-old Ada Lovelace, a mathematical genius and daughter of the famous poet Lord Byron, teams up with fourteen-year-old Mary Godwin, a creative storyteller and future author of Frankenstein. When a priceless jewel called the Moonstone is stolen from a young heiress, the newly formed Wollstonecraft Detective Agency takes on its first case. Using logic, observation, and daring, the girls navigate a world of suspicious servants, secret societies, and Victorian society to solve the mystery.