Okay, the shine is off the term 'high concept', I know. I'm not even sure what the big buzz words to describe how to crystallize your storyline for a powerful pitch are right now.
It doesn't matter. The more directly you can put the basics of your story, the more chance you have at getting a reader's (editor, agent) interest. Examples: The DaVinci Code (you know DaVinci, smart guy, and there's a code... a secret - and away you go). The Flying Nun (there's this nun who can fly, that's going to figure in every plot).
Today I found a new one while grocery shopping. The Honeycrisp apple. If you have not tried one of these get the store immediately! These apples deliver on the promise of their name from the moment your teeth sink in and break the taut yellow and red skin - crunch! And juicy, so juicy it splashes on your cheeks and drips down your wrist.
Delicious to the eyes, the ears, the tastebuds, and to the memory. This is what autumn should taste like. Fresh and full of promise, sweet but not syrupy. Nourishing enough to satisfy and yet looking forward to your next fix.
Writing should be like that. It should get the reader a little messy with the story splashing off the page and nourish without overfilling (leave room for your reader to bring something of their own to the table!). It should begin with an unmistakable promise. This will be good... pick it and enjoy.