The Curse of Renwyk, Book 4 in The Chronicles of Gil-Lael

Raoul made his living as a protector, escorting people through dangerous territory. But his new client was traveling to the most dangerous city in the world, Terrel, Gil-Lael. Not only that, but Larke's clothing announced that she was a member of the religious cult, Adeptes de L'illuminé. A cult most people were suspicious of. So far he'd saved her from rape, and murder. But when they reached Terrel, he must save her from the mad king. To make matters worse, he'd fallen in love with her.