A simple story, really. Man breaks the law. He is punished. He is hung. And then there is an occurrence at owl creek bridge. 
 The ending is what elevates the story being dolefully simplistic to the one with a dramatic flourish. The twist does come out of nowhere and changes the entire story and the perspective of the narration. This kind of storytelling can be both compelling and exhausting at the same time. In this story however, Ambrose Bierce wins.