Parents in South Park become gripped with fear that their children will be abducted, which leads to them taking more and more extreme measures to ensure their safety, finally culminating in a giant wall being built around the town.
With the media full of school shootings, terrorist threats, and child abductions, the parents of South Park grow concerned about the safety of their children. Tweek is scared the most by the media reports, and his parents serve only to exacerbate his fears by turning their house into a virtual prison and conducting random drills.
The next night, the Ghost of Human Kindness appears in his room and takes him through town to show him that there are still friendly people out to help each other in the town. But the Ghost of Human Kindness turns out to be a child abductor himself; he is arrested just before he can lure Tweek into his van.
Now the parents are on high alert. They buy grotesque helmet-like tracking devices for their children named and have the owner of City Wok, Mr. Lu Kim build a huge wall around the city similar to the Great Wall of China. Mr. Kim is offended for them thinking that just because he is Chinese that he can build an enormous wall around the town single-handedly, but after an impassioned speech by Randy, Mr. Kim reluctantly agrees and does build the wall. He is almost finished when a band of Mongols appear out of nowhere and attack the wall. Mr. Kim drives them off by throwing bricks, then proceeds to finish the wall, while wondering why whenever Chinese people build a wall, Mongolians try to knock it down. The Mongols soon return, but when Mr. Kim arrives to drive them off, he finds only their hats and cloaks propped up on branches and a tape recorder playing battle sounds; the real Mongols are back where Kim was before. They break off their attack, but only after putting a large hole in the wall.
The wall soon takes effect as nobody can enter South Park, not even the opposing team for the boys' baseball game. Mr. Kim in the meantime, builds himself a home-made missile launcher to fire heat-seeking missiles at the Mongols. They soon show up, brandishing a baseball, and Mr. Kim fires. The Mongols simply light the baseball on fire and throw it at the wall, causing the missile to make a round trip and put another huge hole in the wall. Again, the Mongols ride off, laughing. When the news reports that most children know their abductors, the parents start to distrust each other and (much to children's chagrin) accompany their children everywhere. Meanwhile, Mr. Kim now has a new scheme: to pour sticky sweet and sour pork sauce on the attacking Mongols. A Trojan Horse (gift-wrapped with a pink ribbon) is wheeled up to the city gates. Mr. Kim sees through the ruse and goes to the horse with a battle-axe, pretending not to know. When he opens the horse though, he finds himself stuck in his own trap, the Mongols having cleverly filled the horse with pork sauce of their own. After they break another hole in the wall, Mr. Kim is "freed" by a hungry dog and swears revenge.
After a news report stating that the parents are most likely to abduct their own children, the parents send them out of town to live on their own, fearing they will abduct their own children despite the fact that they obviously love them dearly. A few days later, the parents wonder how their children are doing. The children are then shown to have joined the Mongols, sitting around a roaring campfire, enjoying meat on the bone, and dressed in fur, silk armor, and helmets; and apparently able to speak fluent Mongolian, though there are no subtitles. The Mongols then move on the wall again, where Mr. Kim is dressed for battle. He then does his "war dance", but while he is doing this, the children wheel a large cart laden with explosives in behind him and blow up the wall. The parents arrive to investigate the explosion. The parents and children are reunited. Mayor McDaniels orders Mr. Kim to tear down the wall, much to his chagrin. The episode ends with Stan saying "Jesus Christ, dude, they've done some stupid crap before, but Jesus Christ" to Kyle.