After their class trip is cut short, students at West Ham High School return home to discover their town is completely empty.

Cassandra and her friends prepare for an uncertain future, while Harry's crew just want to party; Sam and Becca make a discovery.

After the boys ransack the store, Cassandra rallies the girls to exert their power; The students plan a prom; Kelly discovers a family secret.

A shocking event puts everyone on edge; As chaos sets in, Allie's friends urge her to step up and lead; Geordie conducts 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 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 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 spots something suspicious in a photo; Becca goes into labor; The expedition returns with news.