The Wintermen: Seasons Change Series Book 2 of 4

Frank Writeman's search for his son, Jack leads him to New York City, a major hot spot for unclaimed vampires. He soon partners up with Dr. Harold Robinson, a mentally unstable werewolf hunter, in an effort to find his son before the mysterious Wintermen, a race of mutated vampires who want to claim Jack for their own growing ranks. With Frank's fragile probation with the werewolves and Harold's tendency to shoot everything in sight, Jack's chances of being rescued grow more unlikely with every passing day.