After the shocking revelation at the end of Insurgent, when everyone learned that the factions did not simply evolve the way that they had been led to believe, society is left in even greater turmoil.
While some believe that the faction system should be completely abolished, others still feel a strong allegiance to the only way of life they've ever known. Meanwhile, a smaller group is determined to venture outside of the walled-in city to discover the full truth behind their existence.
The truth, it turns out, is nothing that they ever could have imagined, and understandably difficult to adjust to. With a history of genetic manipulation and the government's repeated attempts to correct their mistakes, the great moral question of genetic superiority/inferiority has become an increasingly heated source of conflict. Now Tris and the others must decide which side they will take.
None of those answers come easily, and while everyone struggles to come to grips with their new reality, Tris and Tobias's relationship (as always) is put to further test. Unlike the two previous books, which were told entirely from Tris's perspective, this one alternates point of view between Tris and Tobias. It's an interesting change, and makes sense as far as the plot is concerned, but it does take some getting used to.
I know that a lot of people had a problem with the ending (with varying degrees of passion and anger.) I won't give any spoilers here, but I will say that it was a bit emotional. Personally, though, I didn't have a problem with it. A "happily ever after" ending to this kind of a story would just seem out of place.
Overall, I enjoyed this one, as I did the rest of the series. It wasn't my favorite (in my experience, the rest of a series rarely lives up to the first one) but it was still a fun, exciting read, and I thought that it concluded the story nicely. I think Roth has quite a lot of potential, and I look forward to seeing how she develops as a writer.