Subtitled "An Ambiguous Utopia", Ursula K. Le Guin's 1974 science fiction novel won all those awards that good sf novels always seem to win: the Hugo Award, the Nebula Award, as well as the World Fantasy Award and the National Book Prize. It's easy to see why; I've just reread it after many years, and it was one of those satisfying, consuming, don't-put-it-down-till-you're-finished reads that most books, sadly, fail to deliver.
The protagonist is Shevek, raised in an anarchist society on a planet called Anarres. Some 160 years before Shevek's birth, a group of dissidents from neighbouring Urras were inspired by the teachings of Odo, who preached cooperation, syndicalism, egalitarianism. The governments of the capitalist nations of Urras dealt with Odo by throwing her in jail and eventually making her a martyr; they dealt with her followers by resettling them on their moon, Anarres. The terms of the resettlement specified that once all who wished to go had left, Anarres would be sealed off from outside contact, except for a few strictly controlled and curtailed shipments each year between the planets: Annares would receive essential goods such as petroleum from Urras and in return would ship back minerals which could only be found on Annares. A few scientists are allowed to send letters and papers back and forth, but that is the extent of communication between the worlds.
The novel's chapters alternate between accounts of Shevek's life and his trip to Urras - the first Anarresti ever to make the journey. Even as a lad Shevek was already somehow outside of his intensely communal society, a loner who grew up to be a physicist so brilliant that he had no real peers. Anarres is poor, dry, and dusty, with few native plants and no animals above fish and insects; in this harsh environment all Anarresti must put in physical labour for the survival of the community. Urras, or at least the nation of A-Io, where Shevek is invited as an honoured guest of a private university, is much richer, with lush greenery and many consumer goods. But just as Urras has a dark side - male dominance, poverty, suppression of dissent - so does Anarres - stagnation, fear of change, suppression of individuality. So Shevek works to show the Urrasti that he and his people have something to teach them about equality and freedom, just as he tries to show the Anarresti that they must open themselves up to dialogue with the outside world and all its attendant change and uncertainty.
As always, Le Guin takes conundrums of human existence - gender, power, hierarchy - and uses sf to explore different possibilities, showing how, even though there are no easy answers, there is hope for a better world all the same. Highly recommended.