Eve of Darkness (Marked #1)

Thrust into a world where sinners are drafted into service to kill demons, Eve’s learning curve is short. A longtime agnostic, she begrudgingly maneuvers through a celestial bureaucracy where she is a valuable but ill-treated pawn. She’s also become the latest point of contention in the oldest case of sibling rivalry in history...
But she’ll worry about all that later. Right now she’s more concerned with learning to kill while staying alive. And saving the soul she’d never believed she had.