This was what Wyndham did best: he's created horrible futures for us. He was a dab-hand at the nightmare vision. Like 'The Day of the Triffids' and 'The Kraken Wakes', 'The Chrysalids' points to a grim, dystopian future where people struggle to survive and reconstruct lost order and security after a terrible disaster. But whereas the events that led up to the annihilation of most of the human population in The Triffids and The Kraken were explained in detail in those books, the devastation of huge areas of the planet that are described in The Chrysalids, occurred hundreds of years before the time this story begins. The people have not the vaguest memory and no documented reports of how it happened. It seems probable to the reader, from revelations about the after effects of the killer event, that what happened all that time ago was a nuclear holocaust. All the signs point to it, so it's ironic that the people of Waknuk in Labrador, where this tale is focused, have been struggling to re-establish their lives in the image of the much revered 'Old People' and the halcyon days when life was happy and untroubled by the horrors of what they call 'tribulation'. Even though they believe the Old People brought down the wrath of God upon themselves and their descendents, they know nothing of nuclear war. So they're working to redeem themselves in the eyes of God. One way they try to do this is by ensuring the destruction of mutants. Humans must conform to the image of God, as they believe God intended. Any human that deviates from that norm is considered an abomination. Human mutants are sterilized and ejected from the community, mutant animals are slaughtered and mutant crops are burned. Then, quietly and undetected, a different kind of human mutation evolves. For a long time it goes unnoticed, because these new mutants look normal. However, they have certain mental abilities beyond what is normal and acceptable. This aberration isn't discovered by the normals until some bad luck and carelessness draws attention to the change. When the mutation is discovered, the reaction of the community is ruthless. In their hysterical state of fear and loathing, they mean to root out every last abomination. At some level they must understand that this particular mutation, far from dragging them into mutational melt-down, might actually replace them as the dominant species. The future looks bleak for these young people. They must hide their talent or run away, but where can they go? Life in the wild fringes beyond the slowly genetically stabilizing safe region where they live, is a horrible lurid area of unstable biology and lawlessness, and beyond that chaotic zone there is no life in the burnt badlands.
Wyndham was full of apocalyptic ideas and post-apocalyptic strategies for the survival of the human species. His main protagonists are reasonable, well balanced and humane people who are forced by circumstances beyond their control to be practical - taking whatever distasteful steps seem necessary in order to survive. The stories are always compelling and interesting. The Chrysalids is no exception: interesting characters with a bit of depth, a desperate situation calling for desperate measures, and all adding up to a good read.