It all started when a scientist named Paget performed some experiments on dogs, cats, rats and mice in an attempt to heighten animal intelligence. He was only too successful. When a few of the specimens escaped their cages, people were at first amused by the strange creatures. "Paget's pets," they were called. But as they rapidly bred and spread, the new generations combined vastly sharpened intelligence with a new hatred of man, and amusement turned to horror. Here is a universal folk nightmare developed with scientific logic and narrative skill, by one of science fiction's best writers.