Penny is a high school student turned sleuth who also sporadically works as a reporter for her father's newspaper, The Riverview Star.
On her cases she is sometimes aided by her close friend, brunette Louise Sidell, and occasionally Jerry Livingston or Salt Sommers who are, respectively, a reporter and photographer for her father's paper.
Benson, who was a newspaper reporter herself, favored Penny Parker over all the other books she wrote, including Nancy Drew.
At the time of the court case between the Stratemeyer Syndicate and Grosset & Dunlap in 1980, a Penny Parker revival was in the process, but the plans never came to fruition.
Louise debuted in Tale of the Witch Doll and makes appearances in sixteen books overall, (all but Guilt of the Brass Thieves).
Salt Sommers- a photographer on The Riverview Star and part-time airplane spotter, he is a good friend of Penny's.