Helliconia Winter is the third and final book in the the Helliconia Trilogy, the others being Helliconia Spring (1982) and Helliconia Summer (1983). The novel begins at the end of autumn and the planet of Helliconia is moving into the beginning of a winter that will last 300+ years, causing the human-like denizens to suffer greatly from the collapse of civilization that had reached its zenith in summer, including falling prey to the 'fat death' (which causes binge eating, including cannibalism), which in reality changes human physiology in a manner that allows a greater chance of survival during the harsh winter. For the other main dominant species, the Phagors (as pictured on the book cover), winter results in potential dominance once more over the humans (or Sons of Freyer, as they call them...). This is a very basic synopsis of the novel, which is essentially dominated by a world building narrative in its truest sense. Although they are mostly well developed, the principal protagonists are merely actors on a massive environmental stage in which Helliconia and its yellow-orange dwarf star, Batalix, follow a highly elliptical 1200 year orbit around the Type A Super-giant star Freyer. For fans of epic world building novels the Helliconia Trilogy is up there with the best and Helliconia Winter, although not quite as good as the first two novels, is quality science fiction and despite Aldiss' old-school style it is written in an intelligent and compelling manner.
Helliconia Winter is the lesser novel in the trilogy due to a number of factors; the principal characters, such as Luterin Shokerandit from the northern continent of Sibornal, have less agency in the face of declining conditions, whereas in the first two books the world is opening up to great possibilities due to the advent of spring and then summer. This novel includes much more information about Earth's history and the space station Avernus, which orbits Helliconia and transmits footage back to Earth. The depiction of Earth's future is standard science fiction fare, as is what happens to the six thousand inhabitants of Avernus (although there are some pretty freaky descriptions of giant genitalia called 'perambulant pudendolls'). However the main flaw lies in the fact that despite the trilogy being based on fairly hard science fiction concepts, including believable biological and cosmological principles, Aldiss introduces a seam of dubious mysticism into the narrative, which weakens the original premise. Some of the philosophical ruminations of future humanity are also a bit cringe-worthy, which is perhaps fair enough for humans that do nothing all day but pontificate whilst lazing in mobile towns pulled along by the energy of bizarre white lifeforms called 'geonauts'. Despite these minor flaws Helliconia Winter was an entertaining and satisfying end to one of the great trilogies in science fiction.