After the attack on their island home, Ryan and Lily prepare for their journey north to Scotland. Their ultimate aim, to find the Royal Naval forces that are rumored to have landed there. In the hopes of handing over the data Becky brought with her and finding somewhere safe for Cass to have her baby.

The journey won't be easy, the way is long and the country they had known is gone. Those who survived the bleak winter are as big a threat as the evolving zombies that cover the world.