Blood Empire Infiltrated - Luke Irontree & The Last Vampire War, #6

Revenge is a dish best served personally. Luke survived two years in a vampire prison, fighting for his captors' amusement. The only bright spot was meeting Roxi, a fellow captive and powerful vampire hunter. Now that they're free, he wants revenge. But when Roxi disappears, Luke's world is shattered, and he adds a new name to his revenge list - the god that abandoned them both. But he must go on without her as he and his werewolf friends plan their vengeful return to Belgium. As Luke infiltrates the inner ranks of his enemies, he must stay sharp and not let the specter of his broken heart distract him.
 He's surrounded by enemies, and there's no room for mistakes. Especially as the dark god that drives the vampires hunts for him.