Written in the late 60s, during the sexual revolution, Le Guin is still ahead of her time. This story could be seen as foreshadowing of events over forty years in the future from when it was published.
The story is written in first person and is told mostly from the points of view of two characters. Genly Ai is the alien on the world of Gethen, also called Winter, on what is basically a first contact mission. Therem Harth rem ir Estraven is Prime Minster to King Argaven XV of Karhide. Estraven is among only a few Karhiders to believe Genly’s story that an allied group of worlds called the Ekumen have sent him as an Envoy, or First Mobile as the Ekumen calls him. In presenting Genly’s case to Argaven, Estraven is labeled a traitor in a political move by Tibe, who is appointed Prime Minister. Estraven is exiled from Karhide and flees to Orgoreyn, rival nation to Karhide and to the largest city on Gethen, Mishnory. Genly is given the freedom to do whatever he wants. Genly leaves Erhenrang, capitol of Karhide, and leaves Karhide altogether to go on a quest to find other people of Gethen. His quest eventually leads him to Mishnory where he meets Estraven again and tries his case before the Commensals, the governing body of Orgoreyn. He is betrayed and sent to Pulefen Voluntary Farm, essentially a penal farm. Estraven sneaks into the farm and sneaks his dying friend out. The Commensals have reported Genly dead to Karhide. Estraven is eager to catch them in the lie to discredit them but he can’t return to Karhide himself, nor can either of them sneak back through Orgoreyn so they go over the Ice.
The world of Gethen is also called Winter for a reason. It is almost always winter. Summer is brief and extreme but winter is longer and even more extreme. Genly is Terran and is more used to warmer climates. Estraven takes them over the outer edge of world’s north pole to get close to the Karhide/Orgoreyn border. The trip nearly kills them both at one time or another. They make it to a town in Orgoreyn that’s close to the border and inhabited by people more of a Karhidish persuasion. Here, Genly calls the ship that’s waiting in orbit to both rescue Genly and to meet the people of Karhide first, in a political motive.
They continue toward the border and almost make it when tragedy strikes. In a heroic gesture, Estraven sacrifices himself to get Genly back into Karhide. Estraven died in a hail of gunfire. Genly is taken to Argaven and to meet the new Prime Minister, Faxe, who is also the Foreteller of Otherhord Fastness, and who has been appointed in place of Tibe. Faxe is among those whom Genly met on his quest. Genly and Faxe meet the member of the Ekumen ship. Genly returns to Estraven’s home to give his journals to his family.
The books ends on a somber note with a request from one of Estraven’s younger relatives requesting from Genly a story of other worlds.
There is something unique about the people of Gethen. For all that they are humanoid, they aren't human yet Genly is the alien among them. Gethenians have an unusual sexual cycle that is close to lower mammals than to humans. They spend most of their cycle as almost genderless, having characteristics of neither, yet both male and female, masculine and feminine and having no sex drive or impulse. It is during the remaining part of their cycle, what they call “kemmer” that they can become one or the other, male or female, depending on the situation with their partner. A Gethenian could become male and another female and produce offspring. The next cycle, the situation could be in the reverse; the one that was male could become female.
I said Le Guin might have foretold in 1969 of events happening in the early 21st century with this new gender revolution. I think it would be difficult not to draw similarities to what’s being called gender fluidity in society today.
There are many themes presented in the work. Identity, the Other, the Hero, the Quest, and Justice, just to name a few. From a literary standpoint, it is a profound work. From a strictly storytelling viewpoint, I found it slow, though I had to keep reading to see if Genly and Estraven would make it back to Karhide and what would happen next.