Just below the surface among the family of God lives another family tree--one traced in spirit, invisible and ageless, known as the Watchers. For two thousand years they've seen beyond the veil separating this world from the next, passing on their gift through a lineage mostly overlooked. Throughout history they've scouted the borders of the supernatural frontier, but now their survival hangs by a thread. And their fate lies in the hands of a young woman, her would-be killer, and a mystery they must solve....