Dark Enchantment

Description for DARK ENCHANTMENT by Karen Harbaugh:

A shattering act of violence drives Catherine de la Fer to flee into the dark and deadly night. Now a hunted criminal, the wily French noblewoman enlists the services of English mercenary Jack Marstone to teach her the art of self-defense. But she has cast her lot with a man whose terrible secret plunges them into a world of depravity and deadly seduction. Their taboo desire takes them from the moon-shadowed highways of Paris to the treacherous palace of the Sun King--the prey of a highborn enemy with the mind-bending powers of a sorcerer's dark arts. As day becomes endless night, as they enter a place of unimaginable pleasure, France's most notorious swordswoman and her forbidden lover will attempt a daring act of rescue--one that could promise them eternity in each other's arms...or damn them both forever.

This is #2 in Vampires Series.