Every story has a plot. Whether it’s a short story, a novel, a play, or a movie, the most important element is the sequence of events that make up the story. In fact, that’s the definition of plot: the sequence of events in a story.
Just before the Midpoint, it appears the Hero’s going to pull it off, achieve the goal. But at the midpoint of the novel, and the midpoint of Act II, something happens that results in an apparently devastating reversal of the Hero’s fortune.