To me, coming up with a unique hook [catchy gist or draw of the story] is a lot like making wine.
With winemaking, it takes about three months from pressing the fruit to pouring a good glass of wine. First you have to assemble the basic ingredients: fruit, sugar, and yeast, and then let nature take its course.
In writing you have to assemble basic ingredients: the idea, the characters, and a twist, and let the story come alive.
I found that the style I use in writing is similar to the fermentation process. The idea has to bubble and ferment before I end up with something that is useable.
With my last book I had most of the story done before an interesting opening hook came to me. My point is, don't worry. Let the story ferment for awhile - you might surprise yourself.
C. Fern Cook