When an army truck crashes outside a care home and turns the residents there into something nasty, four friends have to deal with the deadly consequences...

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.

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.