While visiting Jefferson's Lake, near the town of Beaverton, Cartman manages to persuade Stan to play in his uncle Roy's speed boat. In a throwaway comment, Stan mentions how cool it would be to drive the boat for real, so Cartman pulls the keys from the glove compartment and suggests that they do just that. Stan is hesitant to drive the boat for fear of getting in trouble. Cartman, however, calms his nerves by promising that he would take responsibility if they were to get in trouble. Stan relents and turns on the boat. Immediately losing control of it, the pair accidentally crashing the boat into the world's largest Beaver dam, causing Beaverton to flood soon after. Going back on his promise, Cartman declares that Stan is in big trouble, that the boat was just some guy's boat that he decided to play in and that he has no uncle Roy.
Afraid of being caught, the two boys agree to hide their involvement, but Stan is wrecked by guilt. That evening at the Marsh Residence, Stan and his parents watch as the news reports on the disaster in Beaverton, where the flood has destroyed homes and left all the residents stranded on their rooftops awaiting help. The reporter overly-sensationalizes the situation by claiming a death toll bigger than the town's actual population, and refusing to give any sort of real information, instead offering wild speculation that is grossly exaggerated such as raping, murder, looting and cannibalism. When people are interviewed about the disasters, the liberals claim its the fault of George Bush, saying that he doesn't care about beavers, while the conservatives claim it was terrorists, recreating 9/11. As the news report finish, Stan follows his parents into the kitchen where he asks if the people will be rescued off their roof tops. However, his parents brush it off, saying they don't know and that's not important compared to trying to place the blame on other people like the mayor of Beaverton and F.E.M.A.
At school the next day, Stan approaches Cartman about the news report, expecting equal amounts of guilt and concern. Cartman however finds the whole thing amusing, and denies responsibility, stating it was the town's fault for being built under a beaver dam, and blaming the people of the town for not getting out of there. Overcome with guilt, Stan begins to question what to do, but Cartman cuts him off, stating he knows that Stan wants to go to Kyle, but shouldn't, as Kyle is a "Jew Rat", with his "Jew Ethics", hoarding his "Jew Gold" and that he will "Jew" Stan out if he confesses the truth. Kyle arrives at the moment, apologizing for not being able to join them at the Lake. When he asks what they did, Stan lies to him with Cartman smiling contently.
Butters then arrives, informing the hallway of students that they found the cause of the flood, and everyone rushes off, with Stan and Cartman expecting to have been caught. The television reporter informs everyone that the cause is of the flood was Global Warming and that all the rumors were true. The Governor of Colorado assembles all the geologists of Colorado (meaning only Randy Marsh), who he claims the Beaverton flood is only the beginning. He explains that this will only lead to more disasters worse than the flood, and analyzes that it will occur, the day after tomorrow. However, other scientists debate the analysis saying that the end of the world will take place two days before the day after tomorrow. A horrified Randy realizes that means today.
Panic explodes, with everyone running around screaming "We didn't listen!" while running back and forth around town, claiming that Global Warming was chasing after them. Much of the town evacuates to the Park County Community Center, and proceed to barricade themselves inside. Watching the news, the entire country is sharing South Park's panic, with the reporters again sensationalizing the news, claiming massive death tolls that are not true. The towns folk begin to place blame on one another for the Global warming. Meanwhile, Stan admits to Kyle that he and Cartman were responsible. Cartman upon realizing this, snaps at Stan for his stupidity in trusting Kyle, while Kyle pleads Stan to tell the truth. Cartman tries to turn it around, by suggesting Kyle use his Jew Gold to help the people in Beaverton. Stan, still not wanting to get in trouble, suggests they help the people of Beaverton themselves.
Randy meanwhile claims that the world has frozen over and that they cannot leave for any reasons. He begins to indicate on a map where the hardest hit regions will be, inadvertently drawing a penis on the map. In Beaverton, the people continue to wait to be rescued. They boys manage to get a speed boat, but like before can't drive it and crash it into an oil factory, which immediately catches fire. The oil spreads into the flood water of Beaverton, engulfing the town in fire as well.
Back at the community Center, everyone notes the absence of Stan, Kyle and Cartman. Stan then calls, but refuses to admit the truth and instead asks for someone to come get them. Believing it to be another ice age outside, Randy, Stephen Stotch and Gerald Broflovski rush out to save the boys, covering themselves as heavy coats and winter gear, despite the weather outside being a very warm temperature. They soon begin to suffer from heat stroke, believing that the cold is causing hypothermia and overheating them.
Meanwhile, the government refuses to help Beaverton, instead attempting to evacuate the southern states because of global warming, only to be told by scientists that it was not global warming that caused the flood. The government rushes to Beaverton, while the boys try and find a way out of the flaming oil factor. The boys try get to the roof, but Cartman stops Kyle demanding his Jew Gold. After first Kyle seems to not understand what he's talking about, but finally as Cartman pulls a gun, hands over a bag around his neck. Cartman however demands the real bag of gold, not the fake one. Scowling, Kyle prepares to hand over the bag, but instead drops it into the flaming water below. The boys are picked up, along with the rest of the town and returned to South Park.
The townsfolk believe Global Warming to be over, until the Government soldiers inform that the real cause of the disaster was Crab People. Stan however loudly admits "I broke the dam!" However, everyone assumes that he's speaking metaphorically and instead making a deep and meaningful statement about everyone 'broke the dam'. One by one, everyone begins to say "I broke the dam!", "I broke the dam!", Cartman takes advantage of this and jokingly says it too. Stan however explains how he broke the dam in full, but no one listens, believing he came up with the first story that came to mind. Instead more of them say proudly "I broke the dam!" Finally Stan just screams "Aw, fuck it!"