The world has been devastated by a virus that has decimated the adult population leaving small children and teenagers to roam the scarred landscape attempting to form some kind of society with dramatic and violent results. Sisters Evie (Catherine Wrigglesworth) and Fran (Emily Forster) have been traveling from town to town, gathering food and finding accommodation as they move from place to place. They keep to themselves; Evie reading chapters from E. Nesbit's classic children's story 'The Railway Children' to her little sister in an attempt to bring a sense of normality to their bleak existence - the novel was a favorite bedtime read as both girls were growing up; their mother (Jennifer Graham) their favorite reader. Finding overnight shelter in a derelict building, the sisters soon settle down only to be awoken by shouts from another room. Investigating, Evie witnesses the beating of a girl. She watches in horror until the mob leaves the building and the girl behind. Tentatively ...