on Fiction University:
Making readers wonder is a good thing—unless they have no clue why your characters are acting as they do, or your world makes no sense.
It’s easy to think plotting is all about the what—after all, the plot is what happens to your characters. But while the what is important to how the story unfolds, the why is what’s driving that story to unfold in the first place. What without why is just action with any motivation.