An environmental catastrophe destroys civilization. Thousands are starving. Millions are dead. Resources are used up, poisoned and polluted. Found among the survivors are the Custance clan. Led by father John (Nigel Davenport) and mother Ann (Cornel Wilde's spouse and frequent collaborator Jean Wallace), the Custance clan sets out on a quest for safety in a savage world that may just end up turning them into the very thing they are fleeing.

Based on a best-selling novel by John Christopher, this combination horror-movie, cautionary tale warns against the dangers of pollution. The tale is set in a futuristic Britain that has been decimated by the sudden onset of a terrible plague caused by environmental damage. Most of the devastation occurs in London. One family flees to the sanctuary of a friend's farm. The journey is treacherous and the clan must fight insane biker gangs and deal with their own personal problems, but eventually, they make it to the farm. Unfortunately, though they were especially invited, the owner's ruthless brother refuses to let them enter and so the desperate head of the family leads a brutal attack.