Brian Aldiss's epic science fantasy trilogy tells how sociologically altered scientists from earth;, living in an orbital observation station, study the conflict between primitive human-like and cattle-like beings on a planet with seasons lasting centuries. Atheneum's summary of the first volume reads as follows.
This is the first volume of the Helliconia trilogy -a monumental saga which goes beyond anything yet created by this master among today's imaginative writers. An entire solar system is revealed, and with it a world disturbingly reflecting our own, Helliconia: an Earth-like planet where dynasties change with the seasons.
In the beginning, a solitary lad, Yuli, sets out from the icy barriers after his father has been captured by phagors. It is winter, the centuries- long Helliconian winter. Yuli enters the priesthood of an underworld where darkness is holy and holiness keeps power over individuals. He learns of warrior mystics called Keepers and of an even more secretive elite, the lascivious Takers. Through trials and wonders, he works his way back to the world of day to found a city called Oldorando, where his descendants recall his name because he rejected his faith in favor of his people.
Later in the history of Oldorando, Aoz Roon, a leader with a dark past, enters the picture; Shay Tal, a sorceress who is his loving adversary; young Laintal Ay, who alters the course of history, and many other memorable characters. Again we encounter the phagors, that beast-species which is man's unalterable rival. Over the years, phagor armies cross a continent to conquer Oldorando-an Oldorando now in the grip of violent change, as winter yields to brilliant spring.
Events and characters and animals stream across the pages of this gigantic novel. Cosmic in scope, it keeps an eye lovingly on the humans involved. So the 5,000 inhabitants of the Earth's observation station above Helliconia keep their eves trained on the events of Oldorando and may long to intervene though the dangers are too great. So we on Earth have them all in our vision in one of the most consuming and magnificent novels of scientific romance.