This book takes up immediately after the third book in the Earthsea series, which was released nearly twenty years prior. The wasting sickness that's afflicted the world still holds sway on the crumbling society and something's still wrong with the magic. Ged's still lost his power, as he had in defeating the evil wizard Cob in the events depicted in "The Farthest Shore". Tenar's a middle-aged widow, vaguely fumbling for a sense of purpose despite having a farm to run - her children are gone and the life she's chosen affords her few options in a strongly patriarchal Medieval society*. And there's a half-burnt child, crippled and broken, abandoned by the parents that tried to kill her in a camp fire.
In keeping with the previous book this story dispenses utterly with heroics and heroes. It's a slow-paced grind over the course of years as the emotionally stunted Ged flees first in one direction and then another, revealing the wizard's life to have been devoid of development or maturity despite his decades of accomplishment. Tenar, on the other hand, is shown as mature and competent - both emotionally and mentally. It's she who arranges for a possible life for Ged and it's she that manages to get the child to safety despite the terrible men who pursue her.
The book has some interesting insights in the difference between male and female power - it's interesting to see in today's world of debilitating political correctness and retrograde masculinity what real feminism could look like thirty years ago.
*Earthsea is an interesting world, I can't think of anything like it in fiction. There are explicitly detailed examples of fantasy elements such as dragons and evil spirits and magic spells, but society is not stable and neither is the magic. In this way, it's not exactly a Medieval Stasis, where life exists in a perpetually stable low-technology state. There are also hints that the planet hasn't been inhabited very long, and other hints that there might be more to the world than the inhabitants of the Archipelago realize - they don't even know of the Sea People, it seems, those who live on rafts that do an annual circuit in the ocean. With some of the mystical elements bordering on science fiction (on of the evil Ancient Ones is described as a talking stone, which sounds to me like sufficiently advanced technology, not magic), I suspect it's something like a Lost Colony settled by space-faring humans who discovered the planet already occupied by dragons.