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 !
After a three day health food convention in Cleveland, Stella and Dee arrive home to find Stella's Uncle Buster being arrested for causing an explosion on Harper Valley Drive with one of his latest screwball inventions. Annoying and intrusive at times, but after a heart to heart talk with her compassionate mom, daughter Dee learns to love Uncle Buster as much as Stella.
At Stella's 25th High School Reunion, Calvin Kendall, an old boy friend of Cassie's, makes a play for Stella, causing the only fight that the two best friends have ever had. When Stella learns that Calvin is married she threatens to tell Mrs. Kendall about his cheating ways unless he repairs the damage and hurt feelings that he has caused her best gal pal Cassie.
Flora Reilly tries to shut down a local mens club, unaware that Mayor Harper and her son-in-law Bobby are members. After Stella gets busted for an illegal lottery ticket and thrown in jail, she discovers from public records that Flora's great grandmother founded the club and entertained men in a burlesque revue.
Stella gets a new job as Mayor Harper's assistant and a bribe from a shady man called Slick. He offers her $10,000 to steal copies of the construction bids for the new wing of Harper Valley's Hospital.
After the Scrooge like CEO of Reilly Enterprises (Flora Reilly) refuses to sign the Holiday bonus checks for all her employees, she is knocked unconscious by a falling Christmas tree. Later, she is visited by three ghosts who show how her miserable life will end if she does not change her evil ways.
A destructive motorcycle gang called The Banditoes has arrived in Harper Valley. The gang's leader, Clutch Breath has informed town matriarch Flora Reilly that they have no intention of leaving unless Stella Johnson goes with them!