Natural Born Angel (Immortal City #2)
by Scott Speer
And now Maddy must face the most difficult choice of her life. She's been offered the chance to become a Guardian. This means entering into dangerous and high stakes training, with no guarantee that she can succeed. But more than that, it would mean leaving her mortal life behind—forever—and allying with the Angels at a time when their relationship with humans is heading for war. . . .