The Simpsons attend a French-Canadian circus (called "Cirque du Puree", a play on Cirque du Soleil), when a demonic blizzard hits Springfield. Much to Bart and Lisa's dismay, everyone has the day off, except for Springfield Elementary School. At school, Skinner shows them a boring Christmas film from 1938, called "The Christmas That Almost Wasn't But Then Was". They watch the movie for hours until the DVD overheats and catches fire, but Skinner puts it out. When Skinner dismisses the kids, they find that they are snowed in, trapping them in the school with Skinner and Groundskeeper Willie, much to their horror. Skinner tries to call for help, but the phone lines are down. When the students become uncontrollable from cabin fever, Principal Skinner's army instincts kick in, and he begins ruling them with an iron fist.
At night, Bart tries to escape by tunneling through the snow, but Skinner catches him. Skinner tries to collapse the tunnel, but it caves in on him, burying all but his head. The kids tie him up in a dodgeball sack and gag him. they then run wild, even getting into a safe with all their permanent records. Upon learning that Skinner makes $25,000 a year, and knowing that he is 40 years old, they figure Skinner is a millionaire. (40 years x $25,000 / year = $1,000,000) When it's pointed out that Skinner also makes money painting houses in the summer, they amend their estimate of his wealth to "billionaire".
Meanwhile, Homer and Flanders use a "snow-plower" (Ned's car with Ned's roofing attached to the front as a plow) to save the kids. They get frozen in ice after hitting a fire hydrant, and Homer's repeated gunning of the engine causes carbon monoxide to flood the car. Flanders and Homer get high from the fumes and wildly hallucinate. Homer hallucinates about belly dancing women who wait on him. They receive a message from Nibbles the school hamster, send out by Skinner, and head for the school. They crash into a salt silo, melting the snow and rusting up the car. The car exhaust makes Homer hallucinate again, making him see Lisa as a camel and Bart as a dancing girl. As Homer tries to kiss the "dancing girl", Bart tries his best to escape, causing the car to crash. Lisa, (as a camel), then says "Merry Christmas from the Simpsons".