The Lure of the Moonflower (Pink Carnation #12) by Lauren Willig

In the final Pink Carnation novel from the New York Times bestselling author of The Mark of the Midnight Manzanilla, Napoleon has occupied Lisbon, and Jane Wooliston, aka the Pink Carnation, teams up with a rogue agent to protect the escaped Queen of Portugal.

Portugal, December 1807. Jack Reid, the British agent known as the Moonflower (formerly the French agent known as the Moonflower), has been stationed in Portugal and is awaiting his new contact. He does not expect to be paired with a woman—especially not the legendary Pink Carnation.