Divergent - Neil Burger

Set in a futuristic dystopia where society is divided into five factions that each represent a different virtue, teenagers have to decide if they want to stay in their faction or switch to another - for the rest of their lives. Tris Prior makes a choice that surprises everyone. Then Tris and her fellow faction-members have to live through a highly competitive initiation process to live out the choice they have made. They must undergo extreme physical and intense psychological tests, that transform them all. But Tris has a secret that she is Divergent, which means she doesn't fit into any one group. If anyone knew, it would mean a certain death. As she discovers a growing conflict that threatens to unravel her seemingly peaceful society, this secret might help her save the people she loves... or it might destroy her.