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

Charlie and Kelly must deal with Kelly's nan while Steff heads off on a dangerous side quest with Finn. Meanwhile the OAPs, led by Cecily, are hungry...

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 situations that the gang encounter. 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 as heartbreaking revelations threaten the town and her family. Meanwhile, residents race against the clock to escape Dambury, but the army have other plans.