Most good stories start with a fundamental list of ingredients: the initial situation, conflict, complication, climax, suspense, denouement, and conclusion. Great writers sometimes shake up the recipe and add some spice.
Initial Situation
Standing around on a bridge, waiting to die
The first few paragraphs of the story set the scene by describing the moments before a man's execution. We don't know who the man is or why he is being hanged, but we do know he is a civilian who has disobeyed military law.
Conflict
A bridge that needs burning
Farquhar learns from a disguised Union scout that Union troops have rebuilt a bridge above Owl Creek. An enterprising civilian could find a way to burn it down, but any civilian caught tampering with the railroad will be hanged without a trial.
Complication
An unsuccessful hanging
Farquhar falls through the railroad ties of the bridge and manages to free himself from the ropes binding him. Now he just has to avoid drowning and getting shot.
Climax
Swimming for shore
Farquhar swims toward shore as the Union soldiers fire on him. Just as they are about to use deadly grape shot against him, Farquhar gets caught in a vortex that flings him on the opposite shore.
Suspense
The long road home
Farquhar makes his way through the forest toward his home. The landscape is unfamiliar and foreboding. Though he has miraculously survived hanging, drowning, and getting shot at, something seems wrong.
Denouement
Home at last
Farquhar reaches the gate to his property. As he rushes toward his wife, he feels a blow against the back of his neck.
Conclusion
Farquhar is dead
Despite his seemingly miraculous escape, Farquhar's body hangs from Owl Creek Bridge.