After their class trip is cut short, West Ham High School students return home to discover their town completely empty.
Cassandra and friends prepare for an uncertain future, while Harry's crew just wants to party; Sam and Becca make a discovery.
After the boys ransack the stores, Cassandra rallies the girls to exert their power; the students plan a prom; Kelly uncovers a family secret.
A shocking event puts everyone on edge; as chaos sets in, Allie's friends urge her to step up and lead; Gordie leads an investigation.
A student's confession leads to an arrest and a trial; Elle experiences Campbell's dark side; Harry's drug use escalates.
Allie questions Elle about Campbell; as the town grows restless while awaiting Allie's decision, Will and Grizz push for harsh measures.
Six months later, Harry sinks deeper into depression; Grizz and Sam bond; Gordie arrives at a theory about West Ham; Elle puts a plan into action.
A Thanksgiving feast takes a frightening turn; in the aftermath, the Guard oversteps its powers; Sam is torn between Becca and Grizz.
Will tells Allie that he has feelings for her; Elle confides in Helena; Campbell pressures Harry to run for mayor; Grizz leads an expedition.
Campbell plots a coup with Lexie and the Guard; Kelly notices something suspicious in a photo; Becca goes into labor; the expedition returns with news.