In a dystopian near future, all adults have fled an oppressive regime to the mainland. The Gateway offers the only chance of survival for teenage siblings Zero and Serger, and their younger sister Wake, who they are determined to save from the violence of the city. But when Zero’s life is threatened, she flees taking the very reluctant Wake with her. So Serger is forced to chase the two sisters down as they battle for survival and fight to find a safe haven.