The Diaries of Sadie Smith

Sadie's life began at the end of the world. She came of age in the aftermath of a cataclysmic invasion and learned to hide from a horrific enemy. Her skill as a guerrilla fighter allowed her to survive. When a brutal incident alters her life forever, she is forced to come to terms with her hatred for her tormentors. Sadie meets a mysterious scientist who thinks she could be the key to shaping the future and saving the present from humanity's deadliest foe.