The Assassin and the Libertine (Vampires in Versailles Book 1)

The fate of France rests on sworn enemies, Daphne de Duras, a duchess-turned-assassin, and Étienne de Noailles, a disgraced noble and vampire. Tasked with killing him for the murder of Madame de Pompadour, Daphne must decide if Étienne is guilty or if they should join forces to uncover the real killer—all while fighting their growing attraction.