Bart catches a 3-eyed fish (named Blinky) in the river by the power plant & it makes headlines about it. State nuclear inspectors find numerous safety violations, and order Mr. Burns to fix them OR ELSE the plant will be closed down. Mr. Burns decides to run for governor, so that he can pass laws that will keep the plant open (by doing away with the regulations which are costing him so much money).
Bart and Lisa go fishing barefoot downstream of the Springfield Nuclear Power Plant and The Springfield Shopper reporter Dave Shutton pulls up just as Bart catches a 3-eyed fish, Blinky. From the resulting publicity the governor, Mary Bailey, calls for an investigation of the power plant and its owner, Montgomery Burns. After an inspection, Mr. Burns is presented with a list of 342 violations, which would cost over $56 million to rectify ($56,088.800 in Smithers' calculator). Distraught, Mr. Burns talks to under-performing employee Homer, who half-heartedly suggests that Mr. Burns run for Governor, which he does. Because Marge believes Mr. Burns is only attempting to gain political office in order to cover up problems at the plant, she wants nothing to do with Homer's campaigning for Burns, even though Homer makes clear he's only supporting Mr. Burns so he won't get fired and that he can still provide for his family. Homer's support for Burns divides the Simpson house, because Marge and Lisa support Bailey. It is unsure whether Bart supports either Mary Bailey or Monty Burns, but he is seen wearing a "Vote for Burns" T-shirt.
Burns' political advisers break the news to Burns that he is not well liked and force Burns to try being friendly and even smile. Burns also does a TV commercial while discussing Blinky with an actor portraying Charles Darwin, who claims Blinky is an evolutionary step. Combined with a smear campaign against Mary Bailey this eventually leads to Burns tying Bailey in the polls. On the night before the election, Smithers and his other advisers suggest that Burns have dinner at the Simpsons' house as an opportunity to put Burns "over the top". To everyone's surprise, Marge serves Blinky for dinner. On the advice of his campaign team, Mr. Burns tries to act as if it does not bother him, but is not able to keep from spitting it out. The cameras flash as the bite flies through the air, but the press is gone and his gubernatorial campaign is over by the time the chunk hits the floor. Nevertheless, it brings the Simpson family back together again.