On September 17, 2014, alien species from Atria, known as "The Atrians", arrive on Earth where people's unwelcoming reactions provoke them, and the two species begin a war. A six-year-old Emery finds Roman, an Atrian who had escaped and has hidden in their shed. The two later become friends; however, their friendship is cut short when the military shoots him. Ten years later when Emery goes back to school after spending four years in the hospital dealing with immune deficiency, officials announce that seven Atrians will attend the same high school. In order to help her friend Julia, Emery leads her to the Atrians' cipher, but are unsuccessful in finding the cure they need. Emery later learns about Roman and how he survived being shot. After a confrontation in school between Roman and Eric, Roman's friends are on a mission to crash an upcoming party, where Eric is attacked by Drake, while Roman is able to escape with Emery when the police raid the party. In the final scene, Roman heals Julia, while his father is shot by Emery's father by accident.