Homer takes Bart and Lisa out on a "special Saturday." It’s Lisa’s turn to choose what to do, and she decides upon the Smithsonian Traveling Exhibit. There, Homer thoughtlessly defaces the Bill of Rights. OmniTouch, the cell phone company sponsoring the show, strikes a deal with Homer: To pay off the Bill’s repairs, he allows the company to put a massive cell phone tower on the roof, with its inner workings in Lisa’s room.

Lisa is indignant. Unsympathetic, Homer tells Lisa that she’ll have to room with Bart. Soon, Lisa’s stomach is hurting from the stress of living with her brother. Homer takes Lisa to Dr. Hibbert, who suggests trying some alternative remedies. When Homer scoffs at this, Lisa reprimands him for his close-mindedness. Realizing Lisa wants to try the remedies, Homer takes her to a New Age store.

There, the saleswoman suggests trying sensory deprivation tanks. During their session, Homer’s tank is repossessed. It then falls off the truck and gets buried by Ned Flanders. Meanwhile, Lisa goes through a series of sensory deprivation hallucinations, finally hallucinating that she is Homer and getting a better sense of how much her father loves her. Homer’s tank sinks into the ground, winds up in a sewer pipe, and then washes ashore on a beach. Chief Wiggum returns the tank to the store. When Lisa emerges from her tank, she tells Homer that she wants to do something that they’ll both enjoy. They end up at the demolition derby.