Gabriel Jordan lives a lonely life on the streets, taking the rare job that usually means spending hours in the cold, waiting for a chance to take a photograph of a cheating spouse. That's how he meets Dr. Aleksei Tennant-who he sees suspiciously jumping from a window of a woman's apartment. Tennant introduces Gabriel to the hidden worlds, magical worlds connected to this one by portals. Gabriel is eager to learn the runes for opening them, Tennant is eager to teach, and a fragile friendship develops amidst a series of murders. These aren't just any murders. The killer has a grudge against the mixture of other races: he doesn't kill humans, only those of the hidden worlds who are producing children of tainted blood. When the killer attacks them directly, Gabriel and Tennant have to team up to find the murderer, even though they're putting themselves, their love, and any chance at a future together, in danger.

Gabriel Jordan, part-time werewolf and full-time private investigator, should be living a happy life. Three years ago, he was a homeless thief; now he’s got a loving partner and a job he enjoys, he lives in a nice house, and he doesn’t have to worry about tomorrow. So why the sudden urge to cheat on Aleksei, the handsome and occasionally deceptive fae he loves? Why does Gabriel feel compelled to flee the life he’s built for himself? Someone’s calling him. Someone’s looking for him. Someone holds his destiny in her hands. The portals to the hidden worlds have become unstable, even dangerous. Fear and madness linger in the dark. Panic and nightmares chase him, but Gabriel can’t fight an enemy he can’t see, and even turning into his wolf form may not be enough to save him.