Difficult to summarize the action without revealing too much. What is certain is that we did not have time to be bored for one second! The adventures and twists turns fast speed. Jostled by the dramatic events they go through, the characters evolve or reveal a hidden face before. Because the real talent of Veronica Roth is that in his series, there is really no nice or nasty. Everyone defends a different worldview, and very clever who can say which side are the truth and the good, or even if they are compatible. Moral dilemmas are occurring at a rapid pace, and often they must be sliced cruelly and unforgiving.
The end does justify the means? The question is as old as the world, and Veronica Roth does not claim to be response: it goes to show the choices that the protagonists, and the good or bad consequences of those choices. If the universe may seem somewhat simplistic (but we will see that there an explanation for that), the stakes of the scenario, them, are complex and nuanced. And if unsympathetic it is, I could not help but be fascinated by how Tris learns to overcome sorrow, pain and terror to keep going somehow - to the point of eventually find downright inspiring. And chain immediately on the third and last volume of the series.