What if...

What if a playboy pilot and a stuffy stewardess crashland on a deserted island while transporting several children to the U.S. from Cuba?

or

What if a woman, running from an abusive relationship, poses as the expected nanny for a famous country singer?

I attended a writers retreat in November and the gracious host, Bob Mayer, taught that when writing, there needed to be a core question that more or less outlined the entire book in one sentence. What is the point of this, you ask? Well, when you're writing the story and you get stuck or need a boost of inspiration, look at your core question and remember what your original idea for the story was.

The two examples above are core sentences for two of the stories I'm working on right now. If I changed those sentences at all, they would no longer line up with the stories I've written because each part of the sentence is an important part of the story.

So, fellow writers, what is the core sentence, original idea for the story you're writing now? If you changed the sentence, would your story have to change too?