"Crystal Blue-Haired Persuasion" is the twenty-third episode of Season 30 and the season finale.
Mr. Burns cuts children's health care benefits for everyone who work at the Springfield Nuclear Power Plant. As the Simpson family cannot afford medication for Bart's ADD, Marge tries out some healing crystals on Bart as a cheaper solution. She starts selling them to other people and word on the street spreads when the crystals help Bart get better grades, or do they?
Due to a slight fall in the profits of the nuclear plant, Mr. Burns cancels the employee's medical care for children. Because the approval of corporate city tax cuts that prevents anyone from getting medical attention from the government, Bart is forced to switch to a generic drug for his ADHD, resulting in strange side effects. Dr. Nick Riviera does not help with the situation, but in a glass shop called FAO Quartz, Marge and Bart discover blue healing crystals, and she decides to use them to compliment Bart's treatment. Three weeks later, Bart takes home a school grade "A" on paper, demonstrating the powers of the crystals.
When the news of Bart's academic success spreads to all the city's parents, who want to use the crystals for personal media, Marge is going to buy more crystals, but the store is closing and the owner gives Marge all the inventory, while she joins a new cult. Marge opens her own glass shop, "Ye Olde New Age", outside the garage, and starts a thriving business. When the materials begin to run out, Lindsey Naegle appears and offers to expand her business, renaming it to Murmur. Lisa is skeptical about the powers of the crystals, while Piper Paisley, who owns a relaxing healing beauty in Shelbyville, Plop, threatens Marge to get her out of business. Marge, ignoring Homer's concerns, decides to open a Murmur kiosk at Shelbyville Mall next to Plop.
At school, Lisa investigates Bart's recent documents and discovers that he has hidden crib notes in the drawings around the classroom, which can only be revealed by the crystals. She convinces Bart to confess to Marge, since he is betraying the only person who has treated him with love and affection. When Bart confesses to Marge that he cheated, Marge's clients get angry and tell him that the crystals did not work. Marge realizes that the crystals only made people's lives worse, so she closes Murmur and gives in to Piper, to her relief. He also tells Homer, who quit his job due to Marge's success and assumed the role of a stereotypical husband who stays at home, to return to work at the Springfield Nuclear Power Plant.
In the label scene, Marge visits former FAO Quartz owner in the cult to see how she is doing. The woman takes the opportunity to escape the cult with Marge. While driving in Marge's car, the cult owner explodes the bridge in an attempt to prevent them from escaping.