The Guardian (Nightwalkers #1)

Although Fala Rainwater has been anointed the next "tsmishian"--a shape-shifter of unparalleled capacity--she can't help getting in the way of her own destiny. When Tumsemeha is resurrected once more, a great and glorious evil comes to devour our world and now hides among the corrupted bodies of Washington's elite. Yet only one man can get Fala close to her hidden enemy....As liaison to the government's most secretive and supernatural sector, Agent Stephen Winter has just as much riding on Tumsemeha's defeat. But who is Agent Winter "really" working for? With an unreadable aura, this enigmatic warlock holds too many secrets, and Fala will need to probe their depths if she is to become the earth's Guardian and save mankind at its darkest hour...