Writing is a flow of information. Authors pick and choose which information the reader receives. He can reveal bits and pieces of the plot as the story unfolds. The audience takes these bits and uses their imaginations to fill the blanks. They make their own spin on the story.
On the other hand, an author can place a situation in front of the reader without explanation. This is a risky gamble. Showing a problem without a solution can be seen as lazy work, which alienates the audience. Using this technique allows an author to place the real twist later, making the situation complete in hindsight.
It’s all about building suspense. How the author does this, balancing the scales and controlling the information, makes or breaks the book. Many of my doubts concerning my stories revolve around what and when to reveal details to the readers. It’s also a source of a lot of fun.