In her post nuclear Holocaust world, overpopulation and feeding the people are the major problems. The third attempted Solution involves conditioned homosexual love for all, and the only babies born are clones of the best two individuals, Her and Him, born to favoured Clone Mums. Some'Professorial' scientists have refused to abandon marriage and heterosexual reproduction, and are an embarrassment. They have developed powerful new strains of cereals to feed the world, but ominous signs of failure and new diseases occur. Has this new world done enough to preserve gene pools in both humans and foodstuffs? Mitchison was one of the first to raise the potential problems of GM crops: her novel remains urgent, thoughtful and relevant in today's world.