In the not so far off future, humanity is faced with severe climate change as the result of global warming. In response decisions were made on how to distribute resources in a way that would help the most people survive. For Gaia, a 16-year-old girl living outside of the Enclave, a walled city, that means basically living a medieval life. Inside the walls, everyone lives with all of the modern conveniences from fine food and all the water they need to elaborate clothes and finery.

Gaia is following in the footsteps of her mother by training to become a midwife. Besides helping the locals with their births, the job also comes with an awesome responsibility. Each moth, there is a quota in which midwives must turn over the first twhree healthy babies they bring into the world to the Enclave, where they will be adopted. This is heartbreaking for the families, but it is also an opportunity for their children to have the best the world has to offer from a formal education to having all of their needs met.

The Enclave holds a dark secret. The small numbers of residents has led to a narrow gen pool, and the result is a growing number of people who are either infertile or carry dangerous genetic diseases, such as hemophilia. The hope is that by bringing the children in from the Outside will help bring diversity in the gene pool, helping to overcome the troubles.

For the most part, Gaia's family is happy with the life they are living. They took the loss of Gaia's two older borthers, Arthur and Odin, with some difficulty, but they continue to live on, knowing that the odds are that both boys will have grown up happy in their new surroundings. Things quickly start to fall apart one evening, when they are taken by the authorities on charges of treason and working against the state.

Gaia can't help but believe the charges are crazy because of who she knows her parents to be. That doesn't stop her from sneaking into the city to try and help them flee. It does not take her long to be captured herself, where she is brought into the system.

It is at that time, that Gaia starts to learn about the horrible failings of her society. The more she learns, the more she starts to realize that her parents did play a role in trying to open their society up to what is happening to the babies taken into the Enclave.

Gaia also finds a surprising ally in Captain Gray, one of the guards in the city who has his own secrets that will help draw them together. It seems that these dark secrets are really well-known by many, but spoken about by few. Gaia knows that she, through actions by her parents, holds the secret that might start their society on the road to betterment.

This really is a great first novel, and I know that I am already looking forward to its sequel Prized. O'Brien does an amazing job of pulling the reader into the world of her characters. She also does a wonderful job of making the reader care about the characters, whether they are good or bad. It is clear that the people living in the Enclave and Outside are all victims of the decisions made generations before, which brings about a certain level of empathy for them all.

The book is sometimes predictable, but it is also filled with surprises. I know that I wanted to keep turning the pages to see what was going to happen to the characters next. Gaia, like most heroes in dystopias, is putting her life on the line in order to make things better. While this starts off as something she is doing only for herself and her family, it becomes clear to her and the reader that these things must be done for the betterment of all.