With similarities to Iain M. Banks' later Culture novels, Winter is visited first by secret observers, then by the envoy Genly Ai, from the 80-world Ekumen, an advanced society of humanoid races descended from or created by the Hain hundreds of millenia before. Genly examines this unusual society and the question of gender identity from an external viewpoint - Le Guin speculates about whether sexual drive might go hand in hand with the ability to nationalise or mobilise for war. On a smaller scale, however, the inhabitants "kill each other in ones or twos" and are capable of political intrigue and rivalry to match anything on Earth. The people of Winter are a slow people but Ai has come at a time of change - at least one nation has become more organised, and if this is repeated elsewhere the stage may be set for war. Ai's arrival itself will have enormous consequences for the planet and its' society.
The hermaphroditic society of Winter initially seems contrived, and at times it's unclear whether this is supposed to be an all-male or an all-neuter society, but it quickly becomes a detailed and consistent reality. This is accompanied by a description of a planet with a severe geology and weather system that has shaped it's inhabitants as much as their gender.