Acceptance concludes Jeff Vandermeer's Southern Reach trilogy, and does a good job of it. Though I wouldn't say "concludes", rather "rides off into the sunset". This volume rotates between four points of view--Control (current Southern Reach directory), Gloria the previous director (who, it turns out, lived in Area X as a child), Saul Evans the lighthouse keeper, and Ghost Bird, who is and is not the biologist from the last expedition. At the end of the previous volume Area X had expanded catastrophically, and desperation is in the air. Control and Ghost Bird have gone into Area X and are exploring.
The book brings out the story of each character while moving things forward. At the heart, there is no comprehending Area X--might be magic, might be an alien life form beyond our understanding (a favored theory), but none of the speculations seem to bring any sort of enlightenment. So the story proceeds with a sort of melancholy horror, a simple sadness. There are signs of resistance within Area X, and Control and Ghost Bird find familiar faces. But resistance appears to be futile.
This is a sort of existential horror/supernatural story, so if you like Camus or maybe semiotics (Vandermeer credits it for inspiration) then you'll fully enjoy this book. Otherwise it's mostly about the writing. Vandermeer is a master of describing the points of energy within a rotting system (rotting, as opposed to breaking or otherwise failing). If the second two books in the series had not been nominated for the World Fantasy Award I might not have picked them up, but in the end am not sorry I did. 3 stars from me.