The Chrysalids is set in the future after a devastating global nuclear war. David, the young hero of the novel, lives in a tight-knit community of religious and genetic fundamentalists, always on the alert for any deviation from the norm of God's creation.
Abnormal plants are publicly burned, with much singing of hymns. Abnormal humans (who are not really human) are also condemned to destruction - unless they succeed in fleeing to the Fringes, that Wild Country where, as the authorities say, nothing is reliable and the devil does his work.
David grows up ringed by admonitions: KEEP PURE THE STOCK OF THE LORD; WATCH THOU FOR THE MUTANT.
At first he does not question. Then, however, he realizes that he, too, is out of the ordinary, in possession of a power that could doom him to death or introduce him to a new, hitherto unimagined world of freedom.
The Chrysalids is a perfectly conceived and constructed work from the classic era of science fiction, a Voltairean philosophical tale that has as much resonance in our own day, when religious and scientific dogmatism are both on the march, as when it was written during the Cold War.