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.