The substance of story is the gap that splits open between what a human being expects to happen when they take an action, and what does happen; the rift between expectation and result, probability and necessity. To build scenes, sequences and acts, we constantly break open these breaches in reality.

As a charge of electricity leaps from pole to pole in a magnet, so the spark of life ignites across the gap between the self and reality. With this flash of energy, we ignite the power of story.*
(Robert McKee)

Robert McKee outlines what is a writer is really up to when creating a compelling story.

A compelling story has the power to reveal to us things that are true about our lives but we may never see unless we enter these breaches in reality when they present themselves to us (order is but a thin veneer covering randomness), where new and surprising possibilities exist, often only encountered between where we are and where we want to be.

(*From Robert McKee’s blog: What is the Substance of a Story.)