Have you read the Tomorrow, When the War Began (The Tomorrow Series #1) series?
If not, immediately stop reading this and buy a copy or reserve it at the library. Those books were some of the best I ever read, for adults or teens, and posed a lot of thought-provoking questions. The basic premise is this: a group of Australian teens go into an isolated area on a camping trip. While they are gone, the country is invaded and the citizens put into prison camps. The teen are forced to become guerilla fighters. They kill and are killed, and none of it happens lightly.
One interesting thing is that Marsden never specified the occupying country, although if I remember correctly, it was thought to be Indonesia. So what race will the invaders be? I'm betting white.
I sure hope the movie is good (and not too many cheesy cheesecake shots of girls in bikinis).