The Outland. Worlds Apart, #2

Embracing her role as the Fifth Watcher, Audrey Montgomery has made a home in the Outland. As the bridge between the Continuum and those who live within it, her mission is clear: identify and protect Outlanders, those born between worlds. When Saffron Jenkins, a gifted Outlander, begins experiencing disturbing mental intrusions, it soon becomes clear she's being hunted-not in the physical world, but through Borrowing, a dangerous process that allows a killer to slip into her mind.
Revealing just enough to torment her, but never enough to be caught, the predator plays a chilling game of cat and mouse. As the connection deepens, Saffron must work with Audrey, Hunter-Audrey's second-in-command-and her own underground network to unravel a conspiracy that threatens not only her sanity, but the safety of the entire Continuum.