After three months of failed escape attempts, cracks start to appear in the dome. Cargill, not wanting news of what he has done to spread around the world, plots to destroy Springfield. The Simpsons see an advertisement for a new Grand Canyon on the site of Springfield. Horrified that their hometown is in danger, Marge and the kids decide to save it, but Homer objects to helping the people who tried to kill them. The family abandons Homer, but are captured by the EPA and placed back inside the dome. After an encounter with a mysterious Inuit shaman, Homer has an epiphany that he must save the town in order to save himself.