Two geologists emerge from caves in the south-west of England to discover that the world they left a few days before has been encased in ice. After wandering for hours through a transformed landscape, they begin to get a sense of what must have taken place - the fall of a giant asteroid. As they begin to adapt to their new world, and to piece events together through their meetings with fellow survivors, the men start to realise that their survival was no accident. Indeed the survival of others around them has been no accident either. And slowly they understand that a far larger conspiracy than they would ever have imagined possible has been at work, putting into doubt almost everything they have ever trusted.