As you can kind of tell from my username . . . . . . I LOVE DIVERGENT. I have read all of the books (including the short stories about Four) and it is so emotional and touching. But so many deaths!! (Not saying who otherwise I'll spoil it . . .)
The movie takes place in Chicago, where it has been split into five "factions", all full of different traits: Amity, the peaceful, Dauntless, the brave, Candor, the honest, Erudite, the intelligent, and Abnegation, the selfless, which is where the main character, Beatrice Prior, is raised.
When a child in the factions turns 16, they take an aptitude test to see which faction they belong in. When Beatrice takes the test, she finds that she has aptitude for 3 factions: Abnegation, Erudite, and Dauntless. This is extremely rare, and getting more than 1 result in the aptitude test is called being "Divergent". Beatrice is told by her test administrator that she needs to hide in a faction so that people will not discover her divergence.
The next day, there is a "choosing ceremony", where the 16 year olds choose if they want to stay in their current faction or transfer to another faction. Beatrice knows she doesn't want to go to Erudite, which she has been taught by her father to despise, so she has two choices now: Abnegation or Dauntless. When her brother, Caleb, chooses Erudite, Beatrice feels like she has to stay in Abnegation for her parents. However, when she chooses her faction, she chooses Dauntless. After jumping onto a moving train, she meets a girl from Candor named Christina. Beatrice and Christina both jump from the train onto a roof a few stories below, where they are lead to a huge hole in the roof. Beatrice volunteers to jump off the building first, and finds that there is a safety net at the bottom. She meets an instructor named Four, and that is when she decides to make a new start by calling herself "Tris' instead of "Beatrice" . . .
The rest is for you to see! It's really an amazing story and movie. Don't forget to read the books (because books are just as good as movies :) )