Reckoning (Fallen Siren Series #2) S. J. Harper Author

Join Agents Emma Monroe and Zack Armstrong.
She’s sacrificed. He’s suffered. They’ve both been betrayed.
Now it’s time for a reckoning. 
Special Agent Emma Monroe has a secret. She’s a Fallen Siren, cursed by the gods and banished to Earth for her failure to prevent the kidnapping of Persephone. As an FBI agent she saves the lives of others believing redemption could be one rescue away.
 
Her partner Zack is a werewolf and former Black Ops sniper who once carried out a string of questionable assignments. Now he’s determined to atone for his past. Ironically, there’s a portion of his past Zack doesn’t remember—an affair with Emma. Giving into their attraction for one another almost led to their undoing. Now it’s back to business as usual.
 
While trying to unravel the mystery behind a series of kidnappings in Southern California, Emma and Zack become entangled with political tensions in the vampire and Were worlds. Not to mention the struggles they face in their relationship with one another. With so much uncertainty, they come to realize the only thing they can really count on is one another…or can they?