LaShawn returns to the high school, followed by a group of people, who present a grave threat to the kids at the school.

With one member of the group in critical condition and time running out, Grover ventures out of the school and finds much more than just supplies.

Everyone's suspicious of the newcomers, especially after weapons start to go missing. Ollie and Anka try to bribe everyone with an unusual plan to get out of the valley.

As suspicions amongst the survivors grow, one member of the group goes rogue. Grover unintentionally reveals a secret and Violet feels betrayed.

Shunned by the group, Grover and Barrett make a difficult decision. A storm prevents the group from escaping the school so they find an imaginative way to pass the time.

Barrett reveals shocking information to Grover that forever changes him. Violet must contend with new friends and new enemies.

The group must defend the school against a lethal new force. Anka and Violet must come to terms with each other in order to save their friends.

Barrett and Grover discover a disturbing conspiracy. Those trapped in the fallout shelter might have found an escape route.

The situation with the intruders reaches a boiling point. Violet puts herself in a dangerous position to save the others.