Genly Ai, the Ekumen’s envoy to the planet Gethen/Winter, is dealt a setback in his mission to recruit Gethen to the Ekumen when Therem Harth rem ir Estraven, formerly Ai’s ally, withdraws support. Estraven has fallen from favor with Karhide’s King Argaven XV because his efforts to avoid a war between his country and the neighboring nation of Orgoreyn have caused the king to lose shifgrethor, a complex Karhidish version of honor. Estraven tries to explain to Ai that his new coolness toward the Ekumen is a ploy to keep his dishonor from infecting the Ekumen’s mission, but Ai, a stranger to the intricate subtleties of shifgrethor and still unused to Gethen’s politics, fails to see anything but betrayal in Estraven’s actions.

Ai’s alien nature haunts his mission. He is unused to the planet’s intense cold, its complex cultural codes, and, most of all, its unique form of human sexuality. Gethenians are ambisexual, uninterested four-fifths of the time, then intensely sexual during “kemmer,” when they might manifest as male for a kemmer or two, then female during the next cycle. Ai persists in trying to interpret Gethenians as men or women, even though intellectually he knows better. The Gethenians face a similar problem in that they view Ai’s persistent maleness as a perversion.

Ai meets with the king on the day Estraven is banished from the country. Argaven, although suspicious of the Ekumen and Ai, nevertheless gives the envoy freedom to travel throughout Karhide. Ai uses his freedom to explore, and he meets with the Handdara Foretellers, who practice a meditative religion based on unlearning what culture has taught them. For the price of two rubies, the Foretellers undertake to answer Ai’s question, Will Gethen join the Ekumen within five years? Their answer, after a harrowing ceremony, comes back as a single word—yes.

Ai applies for admission to the neighboring country of Orgoreyn, where Estraven has fled after his banishment. Estraven’s influence gains him swift entry, and Ai immediately notices differences between the nations: Karhide is feudal and anarchic; Orgoreyn is socialistic and totalitarian.

Ai’s first night in Orgoreyn is disrupted by raiders from Karhide, involved in the same Sinoth valley land dispute that has cost Estraven his position. Ai’s escape from the raiders puts him in contact with the Orgota, who strike him as an excessively passive people, in contrast to the highly individualistic and passionate Karhiders. He spends a night locked in a grain bin with others displaced by the raid, then is recognized by officialdom and given a vehicle and a pass to take him to the capital city, Mishnory, where he is welcomed by Commissioner Shusgis.

For a while, Ai is feted by the Commensals who rule Orgota, but then subtle changes occur. Estraven, living in the capital, recognizes that no news of Ai’s presence has been communicated to the rest of the country. His diplomatic experience has taught him that, in this country ruled by secret police, this is a bad sign, and he hurries to warn Ai. The envoy distrusts Estraven too much to take immediate action, however, so when government agents come to arrest him in the night, they face no opposition.

Ai is taken first to Kunderer Prison, where he is drugged and questioned for days on end. Then officials load him onto a truck with dozens of other prisoners and send him on a nightmarish journey to a voluntary farm. The envoy nearly dies on the journey; the truck is unheated, the prisoners are not fed, and, at the standard rate of twenty-five miles per hour—not including long, inexplicable stops—the...