A horrific crime that defies ordinary explanation. A rookie FBI agent in dangerous, uncharted territory. An extraordinary hero for the ages. Odessa's life is derailed when she's forced to turn her gun on her partner, who turns suddenly, inexplicably violent while apprehending a rampaging murderer. The shooting, justified by self-defence, shakes Odessa to her core and she is placed on desk leave pending a full investigation. But what most troubles her isn't the tragedy itself - it's the shadowy presence she thought she saw fleeing the deceased agent's 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 in the New York office. What she finds there will put her on the trail of a mysterious figure named John Blackwood, a man of enormous means who claims to have been alive for centuries. What he tells her could mean he's an unhinged lunatic. That, or he's humanity's best and only defence against an unspeakable evil that could corrupt even the best of us . . .