The 5th Wave is a science fiction novel by Rick Yancey that follows 16-year-old Cassie Sullivan as she tries to survive in a world ravaged by alien attacks. The story begins during the Fourth Wave, when Cassie's little brother is taken away by humans infected with a virus who mimic the U.S. Army. Cassie promises to find Sammy and keep their father safe, but he is then shot and killed by Lieutenant Colonel Vosch, who also destroys Camp Ashpit with an alien bomb. Cassie must then navigate through danger and betrayal to find her brother, uncover the aliens' plans, and stay alive.