London, in the not too distant future, and people are now divided into Pures and Crazies, according to the results of a DNA test, with the Crazies sectioned off to live within 'the City', on the other side of the Community wall. Until the age of fifteen, Ana has lived a privileged existence amongst the Pures, but her whole world crumbles when she finds out that her DNA test was faked, which makes her one of the Crazies. She has just three years before she will be cast out of the Community . . .
But Ana meets Pure-born Jasper and is offered a ticket to freedom when he asks her to Join with him. She looks forward to a 'normal' life, and fulfilling her dreams of becoming a musician. Then, just a week before the Joining ceremony, Jasper goes missing; it appears he is somewhere in the City, and no one knows why. Ana sets off on his trail, which takes her through the underbelly of society and into the pits of the human soul. And as she delves deeper into the mystery of Jasper's disappearance Ana uncovers some devastating truths that destroy everything she has grown up to believe, but she also learns to love as she has never loved before.