As a sneak thief in Regency Era London, 18 year old Flora is the best in town, publicly known as the Night Owl because she dresses as a man when she steals. But Flora does what she does in order to keep her found family of fellow orphans alive, safe, and fed. When Flora hears of a fabulously valuable diamond owned by the new Duke of Danbridge, Antony, she vows to steal it, sell it, and use the profits to leave the world of crime and take her loved ones to a new home by the seaside. But once the Duke meets Flora, he has other plans for her – and entices her to join him on a secret mission to save their country.