The children are riding on the school bus during a snowstorm; Cartman is eating a whole chocolate cake by himself. Ms. Crabtree stops the bus and demands that they all keep quiet, or she will shoot the cute little bunny. The road is closed due to an avalanche, so Ms. Crabtree takes the bus down a detour. She is distracted by an expletive Kyle says and the bus plunges over the side of a cliff into a river and over a waterfall. The bus winds up perched on the edge of a cliff. Ms. Crabtree leaves the bus in search of help; meanwhile the children are left dangling over the edge of the cliff, under the threat that a scary monster will eat them. Ms. Crabtree gets a ride from a passing truck driver; she takes one of the driver's aspirin, only it isn't aspirin, it's a "roofy". Meanwhile, back at the cliff, Stan and Kyle reminisce about one of their past adventures, the time where Cartman had an anal probe and everyone got ice cream. Ms. Crabtree and the driver stop at Pauly Shore's Funny Pit!!, where Ms. Crabtree starts shouting abuse at the stage, which breaks everyone up and she becomes a comedy hit. Back at the bus, the kid with a red shirt, a la Star Trek leaves the bus, and is eaten by the scary monster.
Back at home the parents are worried about their children. In Denver Ms. Crabtree is brought to see a talent agent, she also believes that she's forgotten something. Back at the bus, the children try to figure out who the scary monster might be. They remember the time met the scary monster called "Skuzzle-butt" that had TV's Brent Musburger for a leg, back when they went hunting with Uncle Jimbo, Ned and everyone got ice cream. Then thinking that he might be a monster they recall the time that Mr. Garrison tried to kill Kathie Lee Gifford and everyone got ice cream. In Los Angeles, Ms. Crabtree asks for another "roofy" just before she makes her appearance on The Tonight Show with Jay Leno. Back in South Park, Mr. Mackey tells the worried parents of the children, that they children may have just run away. On the bus, Kenny reminds them of the time that they were on the run from death. Just then the monster rips the top of the bus off and eats Kenny. Ms. Crabtree is a success, but she chooses to give up her new career. Back at the bus, Cartman reminds them all of the time that Fonzie jumped his motorcycle over a bunch of school buses, killed Kenny and got an ice cream cone. The children wonder what they are going to do.
The bus is tipping, but children get it stabilized and recall the time when the kid with the red shirt left the bus and was eaten by the monster and they all got ice cream. On the bus, the children see a news report which features their parents singing out to their runaway children to come home. Cartman remembers the time where he found out that John Elway was his father and he got to eat ice cream. Stan and Kyle remind that his father was his mother and the outraged Cartman moves towards them only to have all the activity send the bus hurtling over the edge of the cliff.
In the end it turns out that it was all a dream that Stan was having about Cartman having a nightmare.
Kenny dies when the monster takes him from the school bus; however, one of their later recollections tells about how Kenny was killed by Fonzie when in a Happy Days' flashback he jumped a number of buses with his motorcycle, which then crashed into a wall, crushing Kenny. The boys decide that doesn't make sense; but then these deaths never have, they're just funny.