After the plant fails miserably at a routine fire drill, Mr. Burns organizes a retreat to promote teamwork. Homer misunderstands and brings his family, having to leave them to roam the park looking for things to do. The employees are paired up and race for a cabin at the top of the mountain. Last one there is fired!
Mr. Burns decides to hold a good old-fashioned fire drill in order to excite things up around the Plant. Upon hearing the bells ring, the employees (save Homer) panic and fail to clear the plant within 15 minutes, when recommended clearance time should be 45 seconds. Outraged, Burns declares that everyone will be subjected to a teamwork competition at Mt. Useful. Homer ends up being partnered with Burns while Smithers has to journey on his own, fuming that he was not paired with his boss. The object of this competition is to reach a cabin at the top of the mountain; the last team to arrive will be fired.
Along the way, Burns talks Homer into cheating and they use a snowmobile to reach the cabin. Arriving several hours early, they settle down in the comfortable surroundings. Burns and Homer quickly become friends. However, while clinking their champagne glasses, they inadvertently cause an avalanche that buries the entire cabin. Despite Burns's attempt to operate a telegraph machine or Homer's attempt to dig through the snow, the pair remain trapped. The pair attempt further tunneling escapes, but each time they speak, they cause more avalanches that place even more snow between them and freedom. Meanwhile, Bart and Lisa meet Smithers and agree to help him proceed to the cabin, though they cause more stalling than helping.
Back in the cabin, Burns and Homer are besieged by cabin fever. They build snowmen to pass the time (though Burns insists they build real men out of snow) and clothe them at the expense of their own warmth. The other employees reach what appears to be their destination—however, it is actually a ranger station and they begin to realize that something bad has happened to their colleagues. In the cabin, Homer and Burns stare at each other's eyes, filling their minds with paranoia. They are both driven mad and attempt to kill each other. After a vicious struggle, Burns ignites the cabin's propane tank, launching the building out of the snow and propelling it toward the horrified onlookers. Once it comes to a halt, Mr. Burns reminds everyone of the contest, and all the workers hurry inside.
Lenny is the last person to enter the cabin, and is told he is fired. Burns then decides that no one will be fired after all. The episode ends with Mr. Burns and Homer alternately laughing and glaring at each other.
"Mountain of Madness" was written by John Swartzwelder, although the script underwent many rewrites. The story was completely rewritten and as a result, the plot became odder and quirkier with the scenes of paranoia deriving from this. Before the script was turned in, the script was "very crazy" but a lot of the more insane material was cut. However, most of the rewrites were done during the script writing and did not require any major animation changes. The forest ranger was based on Al Gore who was asked to guest star but turned the role down.