Long road to mercy / David Baldacci.

Her name is Atlee Pine. She is a FBI Special Agent assigned to the wilds of the western US. She has to cover, often solo, vast tracts of area: Wyoming, Montana, Idaho, Colorado, Arizona. Small towns, impossibly long distances in-between, isolation like most on the East Coast have never experienced, and an environment where anything can and does happen. Working with the locals who respect, and also sometimes fear her, and have never really been allowed to know her, Atlee Pine turns her vast investigative skills and unmatched drive to find out the truth. Along the way she will revisit painful memories of her own, come to grips with what she is and what she might one day aspire to be. But in the end, she will have to confront not only a new monster, but also the old one of her nightmares.