She Used to Be My Girl is the fourth episode of Season 16 (originally going to be an episode of Season 15 in production order).
Marge discovers that her high school journalism partner, Chloe (they were the Springfield High version of Woodward and Bernstein), is now a network TV news reporter (while Marge chose to forego college and marry Homer, Chloe broke up with her boyfriend, Barney, to go to journalism school); when Lisa seems more interested in what Chloe has done with her life than what Marge did with hers, she has to sneak out in the back of Chloe's car to attend a U.N. women's conference in Capitol City, only to end up surrounded by lava with Chloe at the base of the erupting Mount Springfield. Can Marge save the day? Is someone out there who can, maybe fly a helicopter to get Chloe out of harm's way? Is this the end of Classic Drunk Barney?
A media circus swarms over the story that Joe Quimby has fifteen lawsuits filed against him. Chloe Talbot is one of these journalists. She spends more time with Lisa. Marge also wonders if she made the right decision by marrying Homer rather than going on to pursue a career in journalism. When Lisa spends too much time with Chloe, Marge gets ticked off at her and they fight for Lisa's affections. Afterwards, Marge doesn't allow her daughter to go on a trip to the UN Women's Conference with Chloe. Lisa skips school and hides in her trunk to go with her. Along the way, Chloe gets a call to report from the erupting volcano and drives to it. Marge and Homer go to where she was heading, but can't find Lisa or Chloe. On a big-screen TV, they see her report and they see Lisa with her. When they get there, Marge saves Lisa from the lava and Barney, Chloe's old boyfriend, saves her with his helicopter.
During the end credits, Lisa is in Chloe's car, and when she discovers her, Lisa prays to the Buddha, Jesus, and SpongeBob saying "There's no time to be picky!" SpongeBob says "Screw her!" and does his crazy laugh. The credits continue as normal.