"The Coon" rises from the trash and takes his place as a lone vigilante who wipes out crime in the town of South Park. A rival superhero appears on the scene in the form of "Mysterion" and challenges the Coon's place as a "symbol" for the town.
Cartman is a wannabe crime-fighting vigilante known as the Coon. He is heard as a narrator at the beginning and other times during the episode. He sees South Park as a city of crime as he sets out to stop crime. He does such acts such as attacking men with women simply kissing in the park. Cartman believes that the men are all rapists and attacks them with claws on his fingers by scratching their faces while men just claim that it stings.
Cartman then goes to the Park County Police Station to report. When Sergeant Yates sees him, he complains about Cartman, and tells him to leave. Cartman reports of another rapist spotted and suspects a plot. The police are aggravated with Cartman as he continually talks. Cartman finally leaves the station, but leaves a box of "Who is the Coon?" shirts, which the officers confusedly pick up.
Cartman goes to the bus stop the next day and inquires about the Coon. Cartman tries to raise praise from the boys about the Coon. After some conversation, Cartman is angry that no one knows-or cares-about the Coon. At school, Cartman makes a speech about the Coon, which no one cares about. He tells everyone that the Coon will be at the roof of Walgreens tonight.
That night the Coon meets Mysterion, another kid crime-fighting vigilante. Cartman accuses him of being a copycat. Mysterion deduces that Cartman is the Coon, due to his large size, though Cartman constantly denies. The next day Cartman suspects different classmates of being Mysterion. Cartman decides to chase Mysterion later, as the first annual Coonicon will begin soon, at the Airport Hilton, where the Coon will appear and have a big party in his honor. No one shows up and Cartman gets angry. A waiter from Airport Hilton makes sure Cartman has everything. Cartman impatiently replies. The waiter wonders if the Coon is Cartman, which he denies, much to the relief of the waiter, who thought Cartman was a douchebag, much to Cartman's anger.
Cartman goes home disappointed when he sees a news report on Mysterion. People are interviewed and give praise, or disagree about Mysterion. Cartman is enraged when he sees Mysterion and not the Coon receive superhero public response.
Mysterion goes to the police station where he is greeted as a hero. He reports various minor crimes such as graffiti and harassment from the movie theater guy. The cops love him and highly praise him. He leaves and meets the Coon, who threatens him to stop. Mysterion lights firecrackers which pop up and leaves. Cartman accuses him of using fireworks which are illegal.
The next day at school, Cartman accuses several students of being Mysterion. He is shocked when he discovers that many students have a picture of Mysterion in their lockers. He is shocked when Wendy Testaburger walks by and asks how Cartman knows if Mysterion is a boy. This instantly angers him, as he realizes the possibility of Mysterion actually being female.
Cartman goes to a U-Store-It alley to meet Professor Chaos for information on Mysterion. Chaos unleashes General Disarray on the Coon, who beats him up. After Cartman calls a truce, he kicks Disarray and demands information about Mysterion. Chaos leads Coon to Disarray's Grandma's storage garage, which serves a secret lair to Chaos and Disarray. Chaos gives Cartman a tour, and shows him his suspects as Mysterion. Cartman is crossed out as he is too fat. Chaos suspects Cartman as the Coon however.
Mysterion visits Kyle in his room and asks him to provide background checks for him. Kyle is chosen because Mysterion thinks Kyle is the smartest.
On the news, Professor Chaos releases a video threatening to blow up a hospital unless Mysterion reveals himself. At a construction site, Chaos asks Coon if a hospital should be blown up; Coon is a superhero after all. Coon/Cartman replies that hospitals have to be blown up for the greater good. General Disarray comments that if they are really evil they should betray Coon and blow him up with the hospital. Coon leaves to get the trigger and Chaos to keep an eye on the TNT.
Mysterion shows up soon after Coon leaves. Disarray freaks out and runs. Chaos fights Mysterion. A crowd gathers to encourage Mysterion. Disarray comes back and fights Mysterion as well. The villains knock Mysterion into a pile of plaster. Mysterion does not move causing the crowd to believe that Mysterion is dead. The crowd cries. A police officer tries to pick off Chaos with a sniper rifle, but Sergeant Yates stops him, asking the officer if he believes the bullet can kill Chaos.
Mysterion soon stirs and the crowd cheers. Mysterion continues to fight Chaos and Disarray. Disarray runs off again. Then the Coon comes back to stop Professor Chaos. The crowd mistakes Cartman as Bruce Vilanch and tell him to be careful, because two superhumans are fighting each other. Mysterion defeats Chaos. Coon comes up and slashes Chaos who runs home crying. The crowd cheers. Cartman says until next time. Mysterion replies that there won't be a next time. Cartman says that crime will continue unless Mysterion reveals his secret identity.
At the police station, Mysterion is about to reveal himself. Cartman/Coon is smiling, but the police plead Mysterion to not reveal his secret identity, or the police will be forced to arrest him for vigilantism. Cartman tells him to go on and says that superheroes have to sacrifice themselves for good. The crowd tells him not to do it. Cartman interjects and tells him to go on. Mysterion agrees and reveals himself. But due to the fact that almost every fourth-graders face in the South Park's animation style looks the same the identity cannot be determined by the audience, coupled with the facts that the crowd does not say the fourth-graders name out loud and that Mysterion does not speak after he is revealed. Cartman says that he always knew his identity all along, although this was likely an effort to save face. Coon thinks through that his plan has worked to become South Park's official hero, while Mysterion is in jail for being a vigilante.
On the Season 13 DVD, there is a deleted ending after The Coon rides off on his tricycle. It shows a police officer closing the jail and saying goodnight to Mysterion. Later, Kyle is seen in the cell, with the real Mysterion showing up and asking why he took the fall. Kyle says he doesn't mind, noting he'll be out in a few days anyway, but asks Mysterion to reveal his identity. Mysterion believes Kyle should know and unmasks himself similar to earlier in the episode, still making it unclear as to who Mysterion really is. Nonetheless, Kyle is amazed and is shocked to find out who he truly is.