A plot must feature a crisis in the life of the chief character in the story

A plot must feature a crisis in the life of the chief character in the story. "A mere chain of happenings which do not involve some change or threatened change in the
hero is going to surmount the barrier, or what forces will enter the scene and finally resolve the difficulty, you have failed in your plot. In a real sense, the plot is the story, and the crisis, is the plot, so be careful of your crisis.
One caution seems important here: not every big story is built on a colossal crisis, for much depends on the results that accrue from the crisis. The main crisis in Maupassant's wonderful short-story, "The Necklace," consists in a woman's losing a diamond necklace borrowed from a friend. Let her husband merely buy another, and what a tepid story you have! But see the years of struggle required to pay the loans made necessary to replace the necklace with one which the friend would not suspect to be a substitution, consider the break-down of fineness and ideals under all this decade of terrible self-denial, and finallyrealize that the years of slavery were practically wasted because the borrowed necklace proved to be only paste after all, and we see how out of a commonplace crisis may grow a tremendous story. So bear this one thing in mind—a crisis is big in proportion as it leads to big things.