Cartman suffers from a mysterious and sudden onset of Gingervitus. Sick and tired of being ridiculed for his red hair, light skin and freckles, he rallies all the ginger kids everywhere to fight against discrimination and rise up and become the master race they are intended to be.
During a class presentation, Cartman present a hate-speech presentation that states "Gingers"—those with red hair, freckles, and pale skin—are creepy and evil creatures who suffer from "gingervitis" and their condition comes from their lack of a soul. He also argues that they cannot stand the sun much like Vampires. He uses Kyle as a key example however of those who are immune to the sun's effect, as he has auburn hair (but not light skin or freckles) and is able to go out in the sun. He dubs people like Kyle as "Daywalker" After his speech Kyle, Stan and Kenny watch as Cartman's speech has encouraged other students to discriminate against gingers, which infuriates Kyle all the more. He opts to do his own presentation about the genetic that causes the birth of gingers and proceeds to interview a family with ginger children. During the interview it soon becomes apparent that although Cartman's prejudiced ideas about Gingers are untrue, the fact remains that the general public, even the parents of three red hair freckled kids, carry a similar bigoted hatred and intolerance toward them (although ironically, the gingers are depicted as being genuinely creepy).
Kyle delivers his speech to the class about the genetics of Gingers, which more or less goes over well enough ("A little too science-y for my taste," observes Mrs. Garrison). However, Cartman continues to undermine Kyle, but citing his status as a "Daywalker" causing his credibility to come into question. Finally fed up with Cartman's bigotry, Kyle the others agree that Cartman needs to be taught a lesson. That night they break into Cartman's house and after subduing him (Kyle strikes him unconscious and then fueled by rage, proceeds to beat Cartman until Stan has to physically pull him off), they dye Cartman's hair red, bleach his skin a lighter hue, and give him henna freckles, to make him look like "a ginger". Both he and his Mother are horrified by the transformation, and Cartman's own doctor suggests that they "put him down" rather than deal with him as a Ginger. Liane considers this, but ultimately decides not to because Cartman is standing right there with her.
At school Cartman suffers from the discrimination that he created with his speech, causing Kyle and the others to think he would finally learn a lesson. Cartman however refusing to admit to his own bigotry and mistakes, instead shifts the blame on to the rest of society, feeling that their dislike of Gingers should not apply to him. As a result, Cartman assembles all the ginger students, and becomes a leader of the "Ginger Separatist Movement", a group with initially claiming that it wants equality citing Ron Howard as a source of Ginger Pride. However Cartman's movement quickly becomes violent and Hitler-esque in tone, as Cartman claims that the only way to fight hatred, is with more hatred. Their first act involves savagely beating a non-ginger actress for playing the ginger role of Annie Warbucks in the musical "Annie". Cartman's group continues to grow in size and Cartman himself begins to preach that gingers are, in fact, the "chosen race," and orders the eradication of all non-gingers from the Earth.
Following Cartman's orders, the gingers abduct as many of South Park's children as they can, including Stan, Kyle and Kenny, after which they bring them to their meeting place the Sunset Room at the Airport Hilton. The Hilton, in order to appease the group, sets up massive lava pit in the center of the Sunset Room, in which the Gingers ritualistically murder them. Kyle as a "Daywalker" is chosen as the first to die, but before the gingers throw him into the lava, he whispers to Cartman that he is not really a ginger, but instead was made up to look like one, by Stan, Kyle and Kenny. Cartman is shocked but the news, and quickly realizes that if his followers were to discover that he was not really a ginger, he would share the fate of the other kids. He quickly tells his followers that he has suddenly had an epiphany, and now realizes that everybody has to get along or else be as bad as the people who persecuted them. The gingers are initially suspicious of Cartman's change of opinion, but Cartman appeases them by singing "Hands in Hand". The gingers begin to free the other children, all of who join in on singing. Meanwhile Kyle mutters to Cartman that he is a manipulative asshole, to which Cartman concedes is true, but doesn't care because he will now not die.