Flora and the PTA members keep tabs on Stella by monitoring her mail, but Stella gets even by planting a phony letter from an imaginary middle eastern princess who just happens to be visiting Harper Valley.
The Harper Valley PTA members accuse Stella of being an alcoholic when she is seen in town gathering beer cans. When Cassie (Fannie Flagg) refuses to throw Stella out of her hair salon, Flora (the town villain) tries to shut her shop down by setting up her snooty daughter Wanda in the beauty salon business.
Stella picks up some extra shifts in the evening doing all the book-keeping for the local business people in town. But, the PTA members jump to the wrong conclusion and think that Stella is practicing the world's oldest profession when she is seen leaving the Harper Valley Motel late at night !
Mayor Harper approves an entertainment license for Kelley's Bar against town matriarch, Flora Reilly's advice. Angered by the mayor's actions, Flora tries to unseat the kindly Mayor Harper by backing her sleazy son-in-law (Bobby Taylor) in the up-coming mayoral election.
A bungling con man holds Stella, Cassie and all of the PTA board members hostage after a failed bank robbery attempt. When he realizes that he has wealthy Flora Simpson Reilly's daughter Wanda among the hostages, he demands 100,000 dollars and a 747 airliner to guarantee safe passage out of Harper Valley.
While taking diction lessons from the married English teacher at Harper Valley High, Stella becomes furious when she receives a sweater with a scarlet A on it from an anonymous member of the PTA board who assumes that she is having an affair !