Beatrice lives with her family in the Abnegation faction. They dress all in grey, wear their hair up, and are completely selfless. Beatrice and her brother are nearing their Choosing Ceremony, where they'll decide which faction to live the rest of their lives in. Before that happens, they have to go through an aptitude test, which indicates which faction they should be in. Beatrice's test shows she's Divergent. She's told to tell no one.
At the Choosing Ceremony, the first shock Beatrice gets is watching her brother Caleb choose the Erudite--the intelligence faction. The second shock is watching her own hand choose the Dauntless--the bravery faction. Once there, she changes her name to Tris and has to learn survival, fighting, and killing to become a full member.
Her days are spent training but she learns quickly how to survive in the brutal surroundings. Then she stumbles upon something that isn't quite right--deals being made between the Erudite and the Dauntless, aimed at the Abnegation. And finding that being Divergent means she can manipulate simulations, which means she may have a chance to save her family.
On the same bent as the Hunger Games by Suzanne Collins and Enclave by Ann Aguirre, we've entered another dystopias, this time in Chicago. The story moves quickly, the characters are well-drawn, and Tris is a great narrator. Some things are obvious, but that's ok. I'm sure there will be more--so this sets up a great beginning. Well worth the read!