When Lisa Simpson tells the town of Springfield about their pollution problem, the town reacts and prohibits all pollution into the water. This doesn’t stop Homer, who dumps a pig-waste silo into the water. Russ Cargill decides that Springfield is too dangerous and places a dome over the town, stopping anything from getting in or out. When the town people find out the true culprit behind the problem, they set out off straight for the Simpson’s home. Escaping from the dome, the Simpsons decide to start a new life in Alaska, whilst the remainder of the town disappears.