Werewolf Cop by Andrew Klavan
Zach Adams is one of the best detectives in the country. Nicknamed Cowboy, he’s a soft-spoken homicide detective known for his integrity and courage under fire. He serves on a federal task force that has a single mission: to hunt down Dominic Abend, a European gangster who has taken over the American underworld. After a brutal murder gives them a lead, Zach and his tough-guy NYPD partner Martin Goulart are finally on Abend’s trail. But things get complicated — and very, very weird. Goulart’s on-the-job enemies are accusing him of corruption. And Zach is beginning to suspect that Abend’s evil goes beyond crime—perhaps to the edge of the supernatural. As his investigation continues in Germany, Zach finds himself lured into the impossible. In a centuries-old forest under a full moon, a beast assaults him, cursing him forever. In the aftermath, Zach is transformed into something horrible —something deadly.Now, the good cop has innocent blood on his hands. He has killed—and will kill again—in the form of a beast who can’t be controlled or stopped. Before he can free himself, he’s going to have to solve the greatest mystery of all: How can you defeat evil when the evil is inside you?