The Philosopher Kings by Jo Walton
Set in a society that strives to recreate the philosophical and communal ideals of Plato's Republic, "The Philosopher Kings" follows the lives of the inhabitants of this experimental city-state twenty years after its founding. The narrative centers around the political and personal upheavals that ensue after the death of one of the community's leaders, leading to a quest for vengeance and a journey across the sea. This odyssey confronts the characters with pirates, new societies, and divine encounters, all the while challenging their convictions and the practicality of their pursuit of the ideal. The story is a blend of speculative fiction and philosophical exploration, examining the complexities of human nature, governance, and the pursuit of knowledge and justice.