England, 1813: Lady Arianna Hadley's desire to discover her father's murderer has found her acting the part of a French chef in one of London's aristocratic households. But when the Prince Regent is taken ill after consuming Arianna's special chocolate dessert, she finds herself at the center of a dangerous scandal.

Because of his expertise in chocolate, the Earl of Saybrook, Alessandro De Quincy, is the ideal candidate to investigate this crime. When the Earl's intuition leads to Arianna's exposure, she convinces Saybrook to keep her secret in exchange for help in tracking down the real culprit.

As their search takes them from the glittering ballrooms of Mayfair to the slums of St. Giles, it becomes clear that someone is looking to plunge England into chaos—and Arianna and Saybrook to the bottom of the Thames...