The Counterfeit Lady — Kate Parker

Who would suspect antiquarian bookseller Georgia Fenchurch of leading a double life--as a private investigator for the clandestine Archivist Society in Victorian London? When England's national security is compromised, Georgia must pose as a titled lady to root out a spy...

A cousin of Georgia's dear friend, Lady Phyllida Monthalf, is brutally murdered in her home during the theft of blueprints of a new battleship designed by her husband--who now stands accused of her murder...and treason. The Duke of Blackford, in service to Whitehall, enlists Georgia and the Archivist Society to assist in the investigation. Playing the part of the duke's new paramour, Georgia gains entry into the upper echelons of London's elite, where amidst elegant dinners and elaborate parties a master spy schemes to lay hands on the stolen plans.

The duke is no stranger to the world of international espionage, but Georgia is out of her element in more ways than one. She must not allow her genuine attraction to the duke--or her obsession with finding her parents' killer--to distract her from her role. But when a mysterious stranger threatens to expose her, the counterfeit lady may be in real trouble...