I hate to do this to you. I get the sense that The Hunger Games is going to become one of those things that people who aren’t familiar with it reflexively hate (if it isn’t that already). But it’s pretty much the biggest thing going right now, and I have read the books, so I feel compelled.
And I really loved the first book. I was underwhelmed by the second, and hated the third. In fact, I hated the third so much that it kind of ruined the first two, and it’s hard to have any interest in seeing the movies. But I did like that first book, on which this movie is based, and it lends itself pretty well to this sort of thing.
You can get a summary from essentially anywhere on the internet right now, but basically: it’s some unknown time in the future, and what used to be North America is now a totalitarian regime run from the affluent Capitol, the hub surrounded by the twelve impoverished districts it keeps firmly under its thumb. Over seventy years earlier, the districts staged a failed rebellion, and as punishment, every year each district must offer two “tributes” — teenagers, one boy and one girl — to compete in “the Hunger Games,” a kind of reality show or televised sporting event in which they all try to kill each other in any way they can. The winner is paraded around and treated like royalty, but the others are dead.
So here are how the teams heading into 2012 are like some of the tributes [tons of spoilers likely ahead]:

