The army tighten their control over Dambury as Charlie, Kelly, Finn and Steff go on a rescue mission. Billy's return ruffles feathers. Reunited, Frank and Cecily seek out others to recruit...

Relationship problems and exams aren't the only life or death situation the gang encounters. A split breaks out among the OAPs as a newcomer turns Frank's head away from Cecily.

Charlie and Steff's friendship is tested. Billy sees an opportunity. Gil starts to realise that her task involves more than meets the eye. The residents of Dambury decide that enough is enough.

Billy takes over and heartbreaking revelations come out that threaten the town and her family. Meanwhile residents race against the clock to escape Dambury, but the army have other plans in mind.