The Laundrymen : Blood of the Saucer Men (Laundrymen)

Monster hunters Wade and Bryan have been separated. Bryan has been kidnapped against his will by a mob of aliens fighting for their survival from the persecution of rival vampires. Wade, meanwhile, sets out to find Bryan and save him from his mysterious captors. Doing so puts him in the path of the vampires and their mysterious leader, who offers to help Wade find his friend in return for helping defeat the aliens. With Wade accepting the uneasy alliance, and Bryan pledging to kill the vampires and help the aliens, each finds himself on opposing sides of a timeless conflict. Book 2 in The Laundrymen series of supernatural thrillers.