OK – so you have the high concept. Now what? Well, you have to have conflict. For me, I created a moral dilemma between the protagonist, the ‘monster’ Cheslov, and a local politician who thinks he has a direct connect with God.
Next – ratchet up the tension at every opportunity. I made my protagonist an ex-Navy seal so he could pretty much deal with anything. Made Cheslov part wolf, paranormal. Then went into detail explaining how screwed up the politician is, he’s hooked on drugs due to his wife’s death, etc. Keep ratcheting up.
Then create an outline – and write, write, write to fill in the outline. Don’t worry about adjectives or effect or the best dialogue or even grammar/punctuation.