This movie scared me, but the reality is even scarier.
I hate dictatorships and have sworn a long time ago that if it's up to me, I will never ever be in one again. Not as worker, not as tourist, not as anything. Ever.
As for the story apart from that, as far as I can remember, one of the girls lies and and takes all the blame, in order to free her friend. I think this was essentially the core story of the movie, I was just distracted by the scary things around it.
If so, then it's a story of true friendship and sacrifice - I guess we all don't know how we would behave in such a situation until we're in one (hopefully never).