BBC TV's film about a nuclear attack on Britain

A hypothetical Chinese invasion of South Vietnam triggers a new world war between East and West. In Rochester, Kent, the anticipation of a nuclear attack leads to mass evacuations. When a stray missile explodes, the ensuing firestorm blinds all those who see it. It's not long before the fabric of society is ripped apart from radiation poisoning, a lack of infrastructure and rioting for food and other necessities.