by Ursula K. LeGuin
This book brings the reader to a universe in Earth's distant future. Many worlds, seeded by a parent race of humans, are now unified in a loose confederation called the Ekumen. Genly Ai, an envoy of the Ekumen has been on the planet Gethen for the past two years, gently encouraging the native humans to join the union of worlds. This is a delicate task for a species not given to flight, and just beginning to accept the existence of alien humanity. Gethen is known as Winter to the visitor, an icy planet that maintains a chill to his very bones (and which allows LeGuin to express her extensive familiarity with frozen Antarctic geography). Gethen's inhabitants also display a unique sexuality for which this book is famous. Most of the time, they are asexual, and during a short period each month, called kemmer, they express sexual traits and may become either male or female. This affects their psychology, and Ai's encounters and conflicts with it make up some of the more interesting aspects of this otherwise straightforward novel. Political intrigues and adventures across vast frozen wastes punctuate the story, which is quick and well-written. Ai is befriended by a high official of one nation on Gethen, but Ai is suspicious of motives everywhere he turns, and this is usually because of his misunderstanding of Gethen psychology. This gets him and his ally, Estraven, in all kinds of trouble and imperils Ai's mission from the Ekumen. LeGuin is a most imaginitive author, and uses science fiction for a higher purpose, exploring and inventing situations that leave us curious and thoughtful. The core intention of the book seems to be the buried duality and unity within the Gethenian people. While intriguingly presented, this goal seemed a little underexplored in the story. The book gets a little loose at times, especially in its political intrigues, but also has stretches of adventure across Winter's frozen wastes.
(This book opens with a brilliant introduction, which is a great exegesis of fiction writing, written by the author in 1976. The Left Hand of Darkness won the 1970 Hugo award and 1969 Nebula award for best novel.)
Also by LeGuin: [The Dispossessed] [The New Atlantis]