Stan is sitting at lunch with the other boys when Butters comes up with a message from Stan's girlfriend Wendy, saying they need to talk. They meet and Wendy explains Stan's hoarding has gotten out of control and she can't take it anymore. An "expert", Dr. Chinstrap, helps Stan go through his locker, while it starts off seeming like the usual adult ridiculousness it soon becomes apparent that Stan really does have a problem. His locker is overstuffed; they find a number of disgusting items, including a maggot infested sandwich and broken toothbrush which Stan refuses to give up. Chinstrap sends him to Mr. Mackey, who doesn't know what hoarding is, only for Stan to deduce Mackey is one himself. After the experts have a conversation with Randy and Sharon Marsh, Principal Victoria, and Mr. Garrison, the two of them- along with Mr. Yelman- a sheep herder, who they mistakenly think is a sheep hoarder, are hooked up to a machine.
As Chinstrap and his assistant, Dr. Pinkerton, explain to Randy and Sharon, the machine will help them figure out why they are hoarders by drifting them to their subconscious. Moments later in Mackey's subconscious he is being bullied by a boy named Billy Thompson, who threatens to attack Mackey at a field trip the next day, when he runs into Stan and the sheep herder, who as the scientists explain in reality, are there because of the power of Mackey's dream. Within the dream, Mackey goes home with Stan, who tries to talk him out of the dream, but Mackey instead plays with his light-bright and old toys. Randy insists he has to rescue his son from the dream despite Chinstrap and Pinkerton's warning he'll be stuck there forever.
The dream moves on to the next morning where Stan, Mackey, the sheep herder and the kids board a bus for the field trip. Stan suddenly sees Randy, who is for some reason a butterfly. Stan asks if he's come to help but Randy reveals while that was his intention, he's more concerned with getting "butterfly poon". The experts claim that they have called in another group of "experts" to go into the dream to create a "dream within a dream", move them into Randy's dream (he'll think it's Matt Hasselbeck's dream), and save them, with one expert providing overly dramatic boombox backing. The second group, the cast of Inception, comes in shooting at people before going into the dream, where they proceed to shoot even more people in the woods as the group arrives. Stan, the sheep herder, and Mackey see Woodsy Owl, an owl mascot with the tagline "give a hoot, don't pollute" perform a song and give anti-littering advice before being put in a work group with Billy and his two friends. It is clear that Mr Mackey was a fan of Woodsy Owl before, and jumps for joy at meeting him, before singing the lyrics of his anti-littering song.
The experts are now seen courting firefighters to get into the dream (because they can bring ladders into a dream) and begin trying to explain the events to Sharon, who claims it all sounds ridiculous and stupid. A pizza guy arrives, since one of the dreamers orders pizza for some reason, and is sent in as well. Sharon is told she doesn't understand because she's not smart. Within the dream, Mackey and Stan are running from the bullies when Stan convinces Mackey to stand up for himself. Mackey prepares for a fight. Back in reality, the experts decide the dream has become too powerful, and at this point they must court "the most powerful dream infiltrator of all time". While he does not wish to come back, the experts convince him to help out a final time.
Within Mackey's dream, the experts and the firefighters arrive and kill Billy Thompson and the tormentors and wait for Mackey to wake up, when he remembers what happened, explaining he ran from the bullies and went into a shack, coming upon that same shack and entering as he mentions he ran into someone who talked nice to him, then "touched him in a real bad place". He opens the door of the shack, only to reveal another younger Mackey being sexually molested by Woodsy Owl. The original younger Mackey becomes very distressed as he relives the memory, and the owl begins trying to take control of the dream, killing Mr. Yelman in the process. Fortunately, he is then killed by Freddy Krueger. Woodsy destroyed, everyone wakes up and the experts explain to Mackey that he must have become a hoarder because he suppressed the memory of Woody's tagline about not polluting as well as the distress of the trauma at being molested by him. Freddy observes guilt he could not save the herder. They suggest Stan move on to his therapy now, but he claims to have a better idea and is seen throwing out the items in his locker. Wendy and Kyle ask him what his problem was and Stan says he doesn't care and doesn't want more therapy. Kyle suggests that "was your therapy" and the first expert comes out again doing over-dramatic boom-boxing again as the episode ends.