Zara and her bridal party leave their Birmingham council estate for a messy hen do in an isolated Welsh cottage. However, the fun gets derailed by the end of the world. With only their hen do paraphernalia and zero survival skills to call on, how will the women fare against Armageddon? With food running out, the hens are forced to break quarantine and venture into post-apocalyptic Snowdonia.

The hens get an unpleasant surprise in a post-apocalyptic mini-mart in Snowdonia. Mother of the bride Bernadette sees a way to turn the situation to their advantage, but it's a high risk strategy, given the secret the women are keeping back at the cottage. In her hour of need, one of the hens gets help from a national treasure.

The hens deal with the fallout of their encounter with their new enemies. Bernadette comes up with an audacious plan to make life better for the bridal party, but it's highly unorthodox, and she faces opposition from the other hens. Shelly tries to make amends for past mistakes but finds herself troubled by unpleasant memories.