Planet Takria. Three continents, but intelligent life exists only on one. In the rest, the natives were killed, downright brutally destroyed by some monsters. Earthlings are trying to civilize the Takriots, who are in the Stone Age, without violence, with minimal interference, but something doesn’t go well: those who have overtaken their relatives in development suddenly lose their minds and begin to destroy everything around them. Why is it that time, which has polished the appearance of the aborigines, has barely touched the thinking apparatus? It’s as if the Takriots were really bewitched. And a strange swamp, in which strange leeches live, spitting bunches of electrons at the aborigines who cross a certain border, but do not pay attention to the earthlings. Secrets, secrets... But the biggest secret began to unfold when one girl looked at the swamp from a height of 3000 meters: the swamp was perfectly round.