A powerful post-apocalyptic allegory of persecution and intolerance, the "Penguin Modern Classics" edition of John Wyndham's science fiction masterpiece "The Day of the Triffids" contains an introduction by M. John Harrison. Nuclear war has devastated the world, bringing with it a host of genetic mutations. In the bleak, primitive society that has emerged from its ruins, any sign of deviation, no matter how small, is ruthlessly rooted out and destroyed. David lives in fear of discovery, for he is part of a secret group of children who are able to communicate with each other by transferring thought-shapes into each other's minds. As they grow older, they feel increasingly isolated. Then one of them marries a 'norm', with terrifying consequences.