Currently listening to The Deception and the Emerald Ring. I am really enjoying this BOCD very much. Here is a review from Amazon.com:

From Publishers Weekly
Harvard Ph.D. candidate Eloise Kelly continues her research of early 19th-century spies in the smart third book of the Pink Carnation series, following the well-received The Secret History of the Pink Carnation and The Masque of the Black Tulip. This installment focuses on 19-year-old Letty Alsworthy, who, after a comedy of errors, quickly weds Lord Geoffrey Pinchingdale-Snipe, her older sister's intended. Geoffrey, an officer in the League of the Purple Gentian, flees to Ireland the night of his elopement. Unbeknownst to Letty, his plan isn't to abandon her; it's to quash the impending Irish Rebellion. When Letty tracks down her prodigal husband in Dublin, not only does she learn of his secret life as a spy, she's sucked into it with hilarious results. Willig—like Eloise, a Ph.D. candidate in history—draws on her knowledge of the period, filling the fast-paced narrative with mistaken identities, double agents and high stakes espionage. Every few chapters, the reader is brought back to contemporary London, where Eloise gets out of the archives long enough to nurse her continuing crush on Colin Selwick. The Eloise and Colin plot distracts from the main attraction, but the historic action is taut and twisting. Fans of the series will clamor for more.