Born of Night The League: Nemesis Rising

In the Ichidian Universe where The League is law, most live in fear. We fight back. Welcome to a world where corrupt assassination politics dominate everyone. It's kill or be killed in, Born of Night, the first book in the #1 New York Times bestselling League series by Sherrilyn Kenyon.

Command Assassin Nykyrian Quikiades once turned his back on the League—and has been hunted by them ever since. Though many have tried, none can kill him or stop him from completing his current mission: to protect Kiara Zamir, a woman whose father's political alliance has made her a target.
As her world becomes even deadlier, Kiara must entrust her life to the same kind of beast who once killed her mother and left her for dead. Old enemies and new threaten them both and the only way they can survive is to overcome their suspicions and learn to trust in the very ones who threaten them the most: each other.