The following short essay is taken from Chapter Six in Build a Better Story.
Unless a story is very short, a single plot will have difficulty holding a reader’s attention. If the story drives from the beginning to the end in a straight line, it lacks complexity. If the story line zigs and dips and otherwise detours from its goal as secondary issues are explored, it increases the reader’s interest. That is the purpose of subplots: to defer the ending of the story and increase the reader’s interest.
Subplots do this by providing a break from the main plot and allow added complications, diversions and trickery to further entertain the reader.
There is a preferred arrangement for organizing the subplots; they should be nested within the main plot. Thus, the story always starts with the main plot. After the main plot gets established, subplot A is introduced. Back to the main plot for a while followed by the introduction to subplot B. The same technique is used for subplot C and subplot D, if necessary. In this structure, subplot A is not as important as the main plot but is more important than subplot B. Subplot C is of less importance than subplot B, but is more important than subplot D. In fact, it is possible with a minor subplot such as D, not to show it at all, but to merely have the characters discuss its progress from time to time.
When approaching the end of the story, subplot D is closed first, followed by subplot C, then B, then A and finally the main plot is concluded.
Have a story that needs to be told? Build a Better Story will help you get it done. The trailer will explain more about the book.