I've ended up reading two 'end of the world' science fiction books back-to-back recently, for reasons of quirky library reservations. The first is Death of Grass by John Christopher, and the other is The Children of Men by P. D. James. I read Death of Grass first, after it was mentioned in a documentary as one of John Wyndham's inspirations. I have to say that it scared the willies out of me. It's not that there's anything particularly horrific about it, but the steady and relentless descent of normal, well-adjusted, civilised people into cold-blooded, calculating killers really disturbed me.
The story is horribly plausible: a potent and highly contagious virus which originates in China destroys all members of the Graminaceae, so all of the major crops (rice, wheat, barley, oats) and pasture grasses for cattle, sheep and goats are totally wiped out. This, not surprisingly, precipitates a world-wide famine, and social order starts to break down as people panic.
The story follows a couple of families who decide to leave London to try to reach John's brother David in Yorkshire, who has a farm located in an isolated and easily-defended valley. Their departure is precipitated by a rumour that the Government is planning to drop atomic bombs on some of the major cities to reduce the population of Britain quickly, making any remaining food reserves go further, and giving at least some of the population a chance of life. It's never made clear in the book whether this rumour is accurate or not, but it hardly matters. People believe it to be true and scramble to leave the cities.
In their journey north, the families gradually gather more people into the group, either because they feel responsible for them, or more often because the incomers can provide resources, guns or protection in numbers against other gangs. Killing others for what they can get gradually becomes normal, as do many other things which would seem morally repellent at any other time. Family becomes more important than any other consideration.
It's a great story, but gave me really disturbing nightmares. Now, I'm just getting in to The Children of Men, which I greatly enjoyed as a film. As people have said, the book is quite different from the film in many ways, but just as tense. In some ways, it's a counterpart to Death of Grass, with different but parallel stresses on society. Rather than pulling closer together into families and bands to try to protect dwindling food supplies, families are ageing and splintering apart as no more children are being born. There are fewer people of working age supporting an ageing population, but more resources and space to go around as the population declines. Where Death of Grass forsees people becoming sharper, and more feral, in The Children of Men, for the most part people seem to be losing hope and quietly giving up.
I think it might be time for a light-hearted, funny book after this one!