FBI agent Odessa's life is derailed when she's forced to turn her gun on her partner, who becomes suddenly, inexplicably violent while apprehending a murderer.
Devastated, Odessa is placed on desk leave pending a full investigation. But what troubles her most isn't the tragedy itself - it's the shadowy presence she saw fleeing his body after his death. Questioning her future with the FBI, and her sanity, Odessa accepts a low-level assignment to clear out the belongings of a retired agent.
What she finds there puts her on the trail of a mysterious figure who claims to have been alive for centuries, and who is either an unhinged lunatic . . .
or humanity's best and only defence against unspeakable evil.