Cassie Sullivan survived the first four waves by being luckier, smarter, and better equipped to deal with the harshness of post-civilization Earth than many around her, but can she outrun the fifth wave that promises to break across the land? Her only choice is to try, because if she falters it might be the end for her younger brother, Sam. Each wave of the attack requires a new skill, renewed vigilance, and pushes the limits of humanity among survivors. Cassie's only chance to save her brother and herself is to trust in a boy who won't share his secrets and may not be who he claims. The 5th Wave sets the stage for a prolonged look at humanity and its' struggle to remain civilized in unconventional times as we follow Cassie and companions through the Midwest and beyond.