Isabel Luna Valdes has long since resigned herself to being the "forgotten" Luna sister. But thanks to familial connections to the Mexican ambassador in London, she is poised to unearth any British intelligence hidden by the ton that might aid Mexico during the French Occupation. Isabel's search is hampered by trysting couples and prowling rogues-including the rakish Captain Sirius Dawson. As a covert agent for the British Home Office, Sirius makes a game of earning the aristocracy's confidence. He spends his days befriending foolish politicians and seducing well-born ladies in order to learn their secrets. But after he spies a certain sharp-tongued Luna sister lurking in the shadows where no proper debutante should venture, it's clear Sirius is outmatched, outwitted, and soon to be outmaneuvered by the one woman he can't resist.