A few nights ago, I watched Argo.
It's actually the second way I saw it, so this time round gave me a chance to think about its story in writing terms.
See... there's actually an awesome lesson in tension in that movie.
It works like this:
Give the main character a shortage of resources. Put him into a very difficult, life altering situation. Then, make sure that even the readers know how tenuous his/her position is.
In Argo, the CIA wants to save six Americans. So you'd think that breaks the resource part of the rule.
Except, things went wrong in Iran so fast that they're left reeling. And the only way they can save the six is by a very far-fetched plan. They can't put together anything better together, because they literally don't have the time.
Why? Because they know the revolutionary guard will find them any moment now, and odds are they'll all get killed.
So not only do we know the stakes early on in the movie, we also know that beating the stakes and attaining the goal is a long-shot. Because there is no James Bond to swoop in and save the day. There are no super powers. And because it's set in the 1970's, there's no internet, no cell phones, no technology that we're used to seeing in the movies.
It works the same way in books. If you have the reader invested in the characters and what will happens to them, things go from zero to incredibly tense if you don't know if they'll actually make it out of the precarious situation they're in. And you'll want them to, more than anything else in the story. And that desire from you vs. all the odds against the desire coming true is where the tension comes from.
In books, a good example it The Hunger Games. We want Katniss to survive, but every single thing is stacked against her. From her own personality to her inexperience, to the government...
Harry Potter is expected to beat Voldemort, but the whole time, you can't help feeling that he's ill-prepared for it.
The list goes on, but I'll leave it to you to to share more examples. :-)