Eugene and Hyacinth Porter are living a nightmare, but they hold on to a glimmer of hope - the possibility of bringing their dead son John back to life through cloning. The road to this however, is perilous, as the earth is now a scorched, flooded, irradiated waste land. Their son John was killed because he, like his mother, Hyacinth, is one of the last remaining 'pure' humans, almost extinct, they are hunted by fanatical robots called Differentialists...