In the last decade of the 21st century, cities and towns are being rebuilt to hold ever larger numbers of people. Genetic engineering and climate engineering convert deserts to farmlands and stimulate luxuriant growth of sea life. Economic refugees are on the move, migrating by the millions. Then come the epidemics made possible by genetic engineering. At first they are beneficial. People start seeing better and hearing better. The sensory enhancements are spread by recombinant DNA through viruses. Despite the good intentions, it is disturbing, and people are outraged that their bodies are being altered without their consent. Then come the memories. Well-meaning zealots release viruses with DNA segments able to trigger the formation of memories duplicated from other people. Paul Navarro, a young engineer, becomes a man obsessed. He remembers a bitter, beautiful woman he has never met, and he goes in search of her. Leila Fonseca has been infected with many of the same memories, and she tries to help Paul. They are far from alone in their struggles. The rapidly changing world is seen not only through their eyes but the viewpoints of biologists, desperate economic refugees, and the feuding leaders of professions more powerful than nations. All of them are learning that change can be beneficial and destructive at the same time-and that the changes can occur inside us as well as outside us.