I started this series at the urging of a friend. She mentioned the she thought I would like it so I picked up Birthmarked. I was immediately sucked I to the world of Gaia Stone and Leon Grey. With every turn of the page I was hopefully for them and leery at the same time. Then came Prized. And although I liked it, it just didn't have the same feel as Birthmarked did. I don't know if I hyped it up too much in my mind or if I missed the deceit of the Enclave and the Protectorat, but something just wasn't there for me. And then there was Promised. Promised saved the series and brought it back to the beginning for me. It was everything that was missing from Prized and more. It was by far the best book of the series and I'm so sad that Gaia and Leon's story is over. 
 Promised picks up roughly where Prized left off. Gaia is leader of the newly formed New Sylum and she is taking all her people across the wasteland back to Wharfton. All she and Leon are asking for from the Protectorat is some fresh water. But when they return to the home they both once fled everything they knew is now different. It is soon made apparent that getting water isn't going to be a simple matter of negotiating. There is a war that is brewing and the arrival of Gaia Stone, the girl that began the revolution, is just what the Protectorat needed to kick it off. Soon Gaia must figure out how she wants to fight and exactly what she is willing to give up for what she believes in. 
 Have I mentioned that I loved this third and final book of the series? I mean LOVED LOVED LOVED it! Every single turn of the page brought me back to the exact reason why I fell in love with Birthmarked. It brought me back to the Gaia I loved and the Leon that loved her. There was something about seeing their fight back that really excited me and made me love Promised even more then Birthmarked. Seeing Leon and Gaia work for something they believed in even if it came at a personal cost for one or both of them was remarkable and truly showed how they had grown not only as individuals but as a couple too. They weren't scared, rebellious kids anymore. They were leaders and leaders with a cause and that cause was the take the vile Protectorat down. 
 Honestly Promised was such a remarkable book that you can tell O'Brien thought through to make sure she gave her readers the ending they deserved. It left me satisfied for sure, but it also left me wanting more from this amazing author and series if possible. Just excellent! A definite must read!