The virus mutates and infects the staple crops of West Asia and Europe such as wheat, barley, oats and rye, while Australasia and the Americas attempt to impose rigorous quarantine to keep the virus out.In order to reduce the British population (then around 54 million) to a level that might survive, the government determines to drop atom-bombs on smaller cities and hydrogen-bombs on the larger ones, like London, Birmingham and Liverpool, having first been barricaded and road-blocked to hold the populace in place so they can be annihilated.
Architect John Custance and his friend, civil servant Roger Buckley, manage to escape London and make their way, along with their families and a loyal gunman and his wife, across an England which is rapidly descending into anarchy and mayhem, hoping to reach the safety of John's brother David's potato farm in an isolated Westmoreland valley in Yorkshire, which he has offered them as a safe-haven in his prescience that society would disintegrate into barbarism as food supplies fell-short. They find themselves in a lawless land and routinely kill for food and self-protection. John's wife, Anne, is a middle class lady who believes that ultimately the civilized nature of humans will prevail, but later both she and young daughter are raped, and she executes one of the perpetrators in cold-blood with a rifle-bullet to the head. She becomes psychologically changed and falls into a depression, and John concludes that more than the horror of the violence done to her and particularly to her teenage daughter, the cause is the awareness that she has lost the bedrock of her own identity.
By the time they reach the valley, they have accumulated a group of 34 men, women and children, and John is effectively a tribal chieftain. John's brother David is unable to allow them all refuge in the heavily defended valley, in which he already has his own entourage, on the grounds there is not enough land to feed so many people. John and his band take the valley by force and in a Cain and Abel type twist, John kills his own brother, since his loyalty to his tribe as their leader is stronger than the familial ties to David. The further cut of irony is that, as boys, their Grandfather promised the land to David realising this was where his heart was and to be a farmer, while John was more inclined to be a city-boy and intent on becoming an engineer. The fragile veneer of civilisation torn from them, it is John who ends-up as master of the estate, having usurped David, the cities now fallen, along with the civilised and symbiotic role of the hinterlands that fed them.
The plummet from an ordered and well-provided-for 1950s to feral existence occurs over a very short time period - not more than a couple of years. Science proves unable to conquer the virus despite an almost religious faith that ultimately human technology would triumph over nature and bring salvation. By knocking-out some viral strains, stronger versions evolved. The only animals that were kept were pigs which can be fed on potatoes, while cattle had to be slaughtered since they need grass to sustain them, supplies of which were dying under the march of the virus. Blame for the emergence of Chung-Li is blamed on the effect on the soil of years over overproduction, the rise of monoculture farming and the excessive use of pesticides to maximise crop yields after the privations of WWII.
It is a coincidence that the publication date of 1956 is the same year that M. King Hubbert first gave his prediction of peak oil, and there is the line, "We found out how to use coal and oil, and when they showed the first signs of running out we got ready to hop on the nuclear energy wagon." Only partly true, as a principal reason for developing "atomic power" was to produce plutonium for atom bombs and nuclear warheads. It has been suggested this is partly why a nuclear fuel cycle based on uranium has been pursued to the exclusion of an alternative fuel cycle based on the far more abundant thorium.
This dialogue is salient too:
"Even if you look at it from the worst point of view," John said, "we probably could all live on fish and vegetables. It wouldn't be the end of the world."
"Could we?" Roger asked. "All of us? Not on our present amount of food intake."
"One picks up some useful information from having a farmer in the family," John said. "An acre of land yields between one and two hundredweight of meat, or thirty hundredweight of bread. But it will yield ten tons of potatoes."
Roger said, "This is a country of fifty million people that imports nearly half its food requirements."
"We might have to tighten our belts."
"A tight belt," said Roger, "looks silly on a skeleton."
"I've told you," John said, "- if you plant potatoes instead of grain crops you get a bulk yield that's more than six times heavier."
Perhaps in past presents, we glimpse our future.
"The Death of Grass," by John Christopher. http://www.amazon.co.uk/Death-Grass-Penguin-Modern-Classics/dp/0141190175/ref=sr_1_1?ie=UTF8&qid=1327314082&sr=8-1