A sophisticated, intelligent new girl named Alex Whitney comes to Springfield Elementary and threatens to overshadow Lisa. Alex is even a hit with Principal Skinner, who lets her organize a school dance. Meanwhile, Homer comes up with a new get-rich-quick scheme: He and Bart will round up as much grease as they can and sell it to a rendering plant. They target the richest source imaginable: the Springfield Elementary cafeteria kitchen. Lisa goes to the dance, but sells tickets outside the gym because she couldn't find a date. At the same time, Homer has crawled through the school's air ducts and into the kitchen, where he uses his wet-dry vac to suck grease out of the stove. But Groundskeeper Willie appears on the scene and tries to prevent the theft. One thing leads to another, and as a result of a misplaced wet-dry vac the school's air ducts fill with the stove's contents. Alex's event is interrupted when the oil begins to drip through the gym ceiling, but no matter--the children of Springfield are happy to frolick in the grease. Lisa is pleased to see her friends acting like kids again and breaks down Alex's uppity facade by goading her into a grease fight.