There’s a touch of time travel in The Just City, and a rabble of robots that may well be self-aware, but please, don’t read Jo Walton’s thoughtful new novel expecting an exhilarating future history, or an account of the aggressive ascent of artificial intelligence. Read it as a roadmap, though, and this book may well make you a better person.

A restrained, if regrettably rapey fable with a focus on exposing the problems with philosophy when it’s applied as opposed to lightly outlined, The Just City takes as its basis a certain social experiment proposed by Plato:

The Republic is about Plato’s ideas of justice—not in terms of criminal law, but rather how to maximise happiness by living a life that is just both internally and externally. He talks about both a city and a soul, comparing the two, setting out his idea of both human nature and how people should live, with the soul a microcosm of the city. His ideal city, as with the ideal soul, balanced the three parts of human nature: reason, passion, and appetites. By arranging the city justly, it would also maximise justice within the souls of the inhabitants.

That’s the idea, at least. Alas, in reality, justice is far harder to achieve than the great Greek believed.

When a nymph named Daphne opts to be turned into a tree rather than share in eros with the god Apollo, said son of Zeus turns to Athene, the goddess of knowledge, to find out why the woman went to such lengths to avoid his affections. By way of explanation, Athene invites Apollo to participate in a realisation of the Republic. He takes her up on her offer by taking on the form of a mortal boy called Pytheas: one of ten thousand ten-year-olds “saved,” as their new masters would have it, from a life lacking liberty.

Simmea comes to the just city Athene teases into being with hope in her heart—hope that here, by learning to live according to Plato’s principles, she can be her best self. She and Pytheas soon form a fast friendship; a friendship Kebes, who met Simmea at the slave market on the day their contracts were bought, and thinks Pytheas preternatural, simply cannot countenance.

But wait, what’s this? Jealousy in the just city, where no one person is to possess, or be possessive of, another? “The ship was barely out of the harbour [and] already the seeds of rebellion were growing.”

Maia is the third of The Just City’s three POVs: a nineteenth-century Yorkshire sort so struck by Plato’s beliefs about the education of women in the world that she wishes, one day, that she could leave her life behind, the better to pursue Excellence in such a perfect place. Unexpectedly, Athene hears her prayer and makes Maia—along with a couple of hundred other philosophical pilgrims plucked from the whole history of humanity—a master.

The masters’ first charge is to build the city for the children to live in. This gives us an opportunity to revel in the text’s superlative setting—“a sterile backwater of history” it may be, but the ill-fated island of Kallisti is alive with promise and possibility—and glimpse of a couple of characters who come into play in a major way later. Unfortunately, Maia’s chapters lag distractingly, isolating her perspective from the other pair by a period of years and disrupting the gathering of the larger narrative.

Walton is wise, in that regard, to compel through character as opposed to plot—of which there’s not, if I’m honest, an awful lot. That said, at the same time as telegraphing some of the more interesting developments ahead, The Just City’s diversity of perspectives serves to keep readers on their feet.

And the three threads do come together eventually, to their creator’s credit. Indeed, Sokrates’ appearance signals a turning point in the novel, on the back of which the book goes from getting-there to great. “He’s like a two-year-old sticking pencils in his ear” at points, yet the fellow is fantastic fun from the first. Compelled to come to Kallisti against his express assertions, the closest thing history has to a philosopher king resolves right away to ruin the Republic—and in the very way one imagines he would: by exposing the problems with its premise through dialogues with everyone (and everything) in the city. Even Maia, who flits around the periphery of the fiction, shares a moment of some significance with Sokrates.

He, then, is the glue that finally binds this book. Without him, it’s a clever question asked of an empty auditorium, but when at last an audience arrives—and with them, the chance of an answer—The Just City is a wonder, as wise as it is witty; a party which rattles along happily until the evening’s over, never mind the absence of incident.

Actually, I take that back. There is incident in The Just City. Several variations on the same incident, I’m afraid, which—whilst well handled—come with a whopper of a trigger warning. There’s such a superabundance of intellectually illustrative sexual violence in this otherwise understated affair that I wish Walton had worked harder to find other ways of exploring free will and equality for all.

Some will have a harder time than others putting aside that oversight in addition to the first act’s failings, but those who do push through can count on a considered account of character and morality that mixes fantasy with philosophy and history with the stuff of science fiction. “It was full of variety and yet was all of a piece. Nobody could ask more.”

It’s with reservations that I recommended The Just City, but I do, to be sure.

The Just City is out from Tor Books on January 13, 2015.

Niall Alexander is an extra-curricular English teacher who reads and writes about all things weird and wonderful for The Speculative Scotsman, Strange Horizons, and Tor.com. He’s been known to tweet, twoo.