The Thief of Eyes by Michael McCaskill

The world is not what it seems. Creatures of myth and legend walk among us. Some just living life like humans do, but others are less interested in such mundane pursuits. Enter the Choir, a clandestine organization that polices the supernatural world in secret and limits the damage from the world behind the veil. In the American northwest, a child away at camp drowns in the middle of the night. This sad but mundane event triggers a doomsday prophecy that could drag the world into oblivion. Allison Piper and Donna "Don" Kyle, agents of the Choir, must race against the clock to unravel the dark future before it is too late.