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, who exist in a state of constant alert for any deviation from what they perceive as the norm of God's creation, deviations broadly classified as "offenses" and "blasphemies." Offenses consist of plants and animals that are in any way unusual, and these are...