I was expecting a straightforward end to this trilogy, with a simple scheme that would set everything right again, that would end the testing. After all, this is YA fiction, and sometimes it's not all that complex. However, our author has a few tricks up her sleeve. The book starts simply enough, with a clear path in which to end the suffering, but then you realise it won't be a easy as it seems, with so many allegiances, secrets and misconceptions. There are a couple of very interesting plot developments, most of which linger in the background and slowly come to their conclusion during the end of the book. This means that you get to work out all the good bits with Cia rather than ahead of her.
We see a fair bit more of Zeen, Raffe and Tomas here, and it is nice to see them developing slightly. However, the largest differences are now seen outside of the main protagonists, with Will, Dr Barnes and the President way in front in terms of character development. Cia seems to have stopped growing and instead finds the need to now hang on to the girl she was before. Here trusting nature is revealed to be more of a strength than a weakness when she finally learns the correct balance.
A very good read overall and a satisfying conclusion, though slightly drawn out nearing the very end. This epilogue part could easily have been drawn out further into a short but instead has been explained away, which is a great shame.
Exciting and interesting, this series has some great world-building and there is some wonderful storytelling involved. It would definitely hold YA interest throughout, especially those who enjoyed The Hunger Games and Divergent.