Plot is the aspect of episodic series most plagued with formula. This is because of a predictable Dramatic Circuit. A Dramatic Circuit is made up of a Potential, Resistance, Current, and Outcome. Each of these aspects must be present to create the flow of dramatic tension.
Conventions have been established that often follow the order indicated above. Each episode begins with the potential for trouble either as the first act in a half-hour series or as the teaser in an hour series. In half-hour series, the next act brings in a Resistance to threaten conflict with the Potential. Hour-long series present an act establishing the status quo that the Potential is about to disrupt, then present an act on the Resistance. Next follows the Current act in which Potential and Resistance conflict. In the final act, Potential and Resistance “have it out” with one or the other coming out on top. Some series favor the Potential winning, others the Resistance, still others alternate depending on the mood of the producers, writers and stars.
Some feel this kind of formula is a good pattern to establish because the audience becomes comfortable with the flow. Sometimes this is true, but unless the Character, Theme, and Domain of each episode varies the audience will wind up getting bored instead. More interesting approaches vary which function of the Dramatic Circuit comes first and jumble up the order of the others as well. Starting with an Outcome and showing how it builds to a Potential, then leaving that Potential open at the end of the story can make plots seem inspired. Many a notable comedy series has its occasional bitter-sweet ending where all the pieces don’t come together.
From the Dramatica Theory Book