An accident places Homer in a cast, and in a position to sue Mr. Burns. This leaves Marge unfulfilled, so she turns to an unexpected source for romance. Meanwhile, Lisa is proclamied "Bus Monitor" and tries to keep the peace.
Homer couldn't locate a parking space at the Nuclear Power Plant, so he plans to park on Mr. Burns' space, as he's on a hunting trip with some friends. Homer then realizes that with Burns out, they can live a bit of his life, so Homer goes around the plant using some of his gadgets and wearing his clothes. However, as he was playing golf in Burns' office, Mr. Burns enters the room.
Homer gets scared and hits the ball, which bounces around until it hits the trapdoor button, making Homer fall into it. However, the pit was under renovation, so it wasn't safe for use yet. Homer hits many objects and construction materials on his way down and eventually lands on a cement mixer that's full of concrete. The accident leaves Homer in a cast. However, he soon gets bored as he can't move his arms to do any activities.
Meanwhile, on the school bus, Dolph tries to fight Milhouse, but he accidentally hits Nelson. Soon after, lots of other bullies are also fighting. With Otto unable to help, Lisa records the fight on her cellphone. She later shows the video to Principal Skinner, who sees that Lisa could solve some of the bus problems, so he promotes her to school bus monitor.
Meanwhile at Burns' office, he finds out that his trapdoor is now illegal as it has to meet with some modern standards, making Homer able to sue the plant. Fearing this, Burns sends Smithers to see Homer and convince him not to do so. However, his visit has the opposite effect, as Smithers reminds Homer to sue Mr. Burns.
Smithers becomes friends with Marge, where they start talking about sewing patterns, but end up talking about their love for Homer/Mr. Burns. Marge starts thinking about kissing Smithers, but Mr. Burns calls him. She then goes back to Homer and they have sex. At Burns' office, Burns gets angry as Smithers couldn't get Homer's signature yet.
At the school bus, Lisa manages to organize the way the kids sit, which makes them quiet. Later, she tries to make other sitting plans, such as for the cafeteria and for the playground. However, the kids are not happy with Lisa's plans and they rebel against it. When the bus arrives at school, it is completelly vandalized and on fire. The kids leave laughing while Lisa is confused as why her plan didn't work. Milhouse explains that the bus is supposed to be crazy, which makes her a bit happier.
At home, Homer realizes that Marge is hanging out a lot with Smithers, and the only way to impede this is if he gives up on the lawsuit, which makes his lawyer crestfallen. To make him feel better, Homer chooses to roll down the courthouse steps, but Marge tries to save him and falls as well. They are run over by a truck and have to wear casts, which brings them a lot closer together.
The episode finishes with Lisa in Ms. Hoover's classroom, trying not to be a know-it-all, but she couldn't handle it and gives all the correct answers, including the day to Hoover's dentist appointment.