The climax is at the end of the second scene where the murder of the boss takes place. If you have watched the play or read the text, pay close attention to the stage directions and what happens while Mr. Zero's boss is dying. There is in fact a climatic staging of music that is supposed to reflect events in the world. The audience is supposed to hear sounds that bring armistice day to mind (11/11/1918-it ended WW I) among other things. But there is also the sound of wind, waves, carnival, a train whistle etc....a barrage of sounds that are perhaps designed to dwarf human existence. Since the play was written in the 20's and it commonly considered one of the first works of Expressionism of American art, it is characterized by a sort of hopelessness and despair of the post-war existence. Even though the 1920's were a time of prosperity America, many artists did not buy into the sentiment that everything was okay and the Expressionists in particular held onto to the idea that art reflected the emotional experience, or perhaps pain, of modern life. It is this pain of modernity, the idea of being replaced, that makes Zero kill his boss.
At the climax, De Spain rides the horse and fires the shots. In this story, Faulkner does not disclose the results of the shooting because the point-of-view character, Sarty, is not in a position to learn about them. The mystery about the outcome is hence a direct result of Faulkner’s use of a consistent point of view. It is possible that Sarty's father ands brother were shot as he trips over something near the end of the story and calls Abner "father" in some sort of eulogy for him. An unlikely tripping at this point ofd the story is somewhat mysterious and lends itself to much ambiguity as to whether or not he eulogized his father at all.
For all his empathy, Sarty has no intention of being an accomplice in the burning of another barn. After he alerts de Spain that the barn is about to be burned his life can never be the same again.The climax of the story occurs at the end when Sarty has alerted Major de Spain of his father’s intentions to burn his barn.