At his house, Cartman is playing on his Xbox 360 when Nanny Stella arrives with her camera crew. She promptly annoys Cartman by taking away his Xbox, so he gets revenge by manipulating her to leave, asking her why she didn't have kids of her own. He goes on to tell her, that it's because she is ugly and she's too old to have kids of her own. Angered and upset, she marches out.
Supernanny also fails to "fix" Cartman, with her ending up in a mental institute feeding on her own feces. Liane asks the doctor treating Supernanny what else she can do, and he recommends another show, The Dog Whisperer.
When Cesar Millan turns up, he instantly makes an impact on Cartman. He treats Cartman like a dog, constantly nipping at his neck, taking him on a walk, leashed, and explaining how he is to be dominated. Cartman is angered so much that he runs away from home. Despite Liane's initial worry, Cesar assures her that he'll return.
Looking for a place to stay, Cartman asks Stan Marsh, Kyle Broflovski, Kenny McCormick, Butters Stotch, Jimmy Valmer and Craig Tucker to stay at their houses, but they all turn him down, and he is forced to stay in an alleyway in the rain, while they play Xbox.
He returns and is angered to see Cesar Milan is still there. Cartman threatens to call Child Protective Services, but Liane finally decides to be dominant, causing her son to be submissive. Cartman begins behaving appropriately soon after, and realizes he's changing for the worse (as he sees it). He devises a plan to kill his mother, but Stan, Kyle, Kenny, and Butters refuse to help.
That night, Cartman prepares to go ahead with his plan, but suffers a strange reemergence of his heavily repressed conscience, which convinces him the changes are for the best. The next morning when Liane comes down to breakfast, Cartman is going over his homework and eating a healthy meal. Cesar pays a final visit, and Liane asks him if he wants to see Madame Butterfly with her, but he explains she is just a client, and he has other work to be done. Liane is disheartened and invites Cartman, promising to buy him a Mega Ranger if he goes. He asks if he could have two, which Liane agrees to, telling him that he can have whatever he wants. This incident culminated in Cartman returning to his "normal" self.