Zombie is at a camp and he has new squad members to help compete against other people in the camp. The new squad members are Poundcake, Flintstone, Dumbo, Tank, Oompa, Teacup, and Nugget (which is Sammy). In a matter of missions, Tank dies, but they get a new replacement for him and her name is Ringer.
With the addition of Ringer, Zombie's squad wins the competition and they graduate from the camp (except Sammy). The general of the camp, General Vosch, calls Zombie after his squad graduates and Vosch talks about how he killed most of the people in the camp when Cassie's father died. After that, Zombie and his squad is sent to go on a mission.
During the mission, there goal is to get missiles and kill personal. In this mission, Oopma dies and Ringer and Zombie find Renzik (Zombie's old drill instructor), and they find out there trackers have kill switches and if clicked can kill anyone with a tracker. Flintstone is shellshocked with the information and flips his own kill switch.
While Cassie and Evan are on their way to the camp, Cassie finds out that Evan is an alien and she gets mad at him. Evan tells Cassie he didn't kill her because he is in love with her. They continue to go to the camp and they find a yellow bus to transport in.The yellow bus was the bus that transported Sammy to the camp. Cassie encounters Dr. Pam and Cassie knocks Dr. Pam out because she was trying to put a tracker on her.
Zombie returns to the base with his squad. Zombie rushes into the camp and gets rid of his tracker with the kill switch on. After he takes out his kill switch, Zombie finds bombs planted in the camp that are wired to explode. While that is happening, Cassie and Sammy are reunited and they manage to escape from the camp.
Ringer picks them up and they drive away to safety. The camp blows up and Cassie wonders if Evan is okay and she can stop thinking about Evan. Cassie and Zombie have a moment and they kiss and they watch the sunset.