In book three of this 12-book series, Ellie and the Winchesters are hunting a pack of vampires that for reasons unknown have managed to kill several other hunters. Sam and Dean are convinced they're pure bloods, but Ellie has other ideas. Ellie and Sam get closer, but something is still holding her back. After a difference of opinion, Ellie decides to finish the case on her own, and finds out the hard way that she'll have to make some big sacrifices to keep the Winchesters safe from her monsters.
A young lone huntress tends to herself and kills the supernatural for a living. She has been training herself for years ever sense demons killed her parents. She lives alone and hides in the shadows. One day she finds herself face to face with two famous supernatural hunters who's names send chills down a monster's spine. The three hunters form an unlikely allegiance. Though skeptical, the famous supernatural hunters form a bond with the young girl and take her as their own and set off on mysterious and dangerous battles. But there is something about this lone huntress that sends unease through her new companions, something that might be a threat to them all.