I’m still reading STORY and have so much to say on its utility that you’ll just have to bear with me for a few more posts on it.
THE GAP
McKee has a theory that the material a story is made of is not words, not paper and pen (or computer) but something he calls the GAP. The Gap develops when a main character acts and discovers that his/her expectations regarding the response s/he’s going to get conflict with the reaction s/he really gets. This discrepancy forces the character to adjust and change.