after the first human contact with the siwannese, the entire race committed mass suicide. so the Terran government made a law-no further contact would be allowed with sentient creatures anywhere in the Galaxy. therefore, Doona could be colonized only if an official survey established that the planet was both habitable and inhabited. but the space step had made a mistake- Dana was inhabitable. now the colonists choice was limited. leave Doona and return to the teeming hell of an overpopulated Terra. or kill the cat like inhabitants. or learn for the first time in history how to coexist with an alien race...