Cosmo annoys his family. They send him away and then he saves Poof. He becomes Super Not-Cosmo and saves the citizens of Dimmsdale from the broken dam and a volcano. However, his "fix" only helps temporarily.
Wanda is changing Poof's diaper. When Cosmo asks if he can help change it. Wanda lets him help. Cosmo "changes" Poof's diaper into a wolverine and says it's a puppy. But Wanda says that it was a wolverine. The then Cosmo poofs up an electric walrus saying that was wolverine. But then Wanda tells Cosmo to sit in the corner of Timmy's bedroom. But then Cosmo sees that there is a loose nail in the wall and pulls it out, making the house collapse on Timmy and Wanda. Then Cosmo is outside of the house for being too annoying. Then Poof follows him. So he goes with Poof to the seesaw. He accidentally makes Poof's seesaw partner a whale. Making Cosmo say "That sure is a big chicken." So Poof flies off the seesaw only to be saved by Cosmo. Then Cosmo races after him, accidentally falling into a jumper, underwear, and a cape, all the clothes of a superhero. And after saving Poof from falling from the sky, he becomes a superhero called Super Not-Cosmo, first noticed by Chet Ubetcha. Meanwhile, Timmy and Wanda are bored, and British, because life is boring without Cosmo. But the two have a food fight. But Cosmo keeps on 'saving' the town. First, Timmy's on his bed when Cosmo hears a Dimmsdale tree cat on a tree thinking that it was stuck up there. So he comes up from under Timmy's bed making Timmy injured by the crash of his bed. Then Cosmo goes up to the Dimmsdale tree cat, takes it off the tree and gives it to the old lady beside the tree. Thinking it's hers, he gives it to her and flies away.
Then, the Dimmsdale Dam has a crack in it, making Cosmo go to the dam and fix it with a bandage. Finally, the volcano erupts and Cosmo rushes to the volcano and fixes it with a cork, (one of those things to keep wine in a bottle) and flies away. But then Timmy and Wanda find out the washroom is Super Not-Cosmo's lair. But then, Chet shouts for help because he can't find his car. Super Not-Cosmo comes and holds onto Chet making both of them fly in the sky looking for his car. But then everything that Super Not-Cosmo fixes backfires. This means the Dimmsdale tree cat was supposed to be in the tree, the bandage was so wet it peeled off and making the cork not that secure because of the lava in the volcano. Then Chet announces that Super Not-Cosmo was a 'super-zero'. Then Chet tells Cosmo to sit in the corner like Wanda, making Cosmo sob. Meanwhile, at Timmy's house, Wanda gets a letter from Cosmo saying he's going to be gone forever or three weeks, whichever comes first. So Timmy wishes up a villain called The Milkman, which says he delivers milk in three flavors: plain, chocolate and eggnog. Then Dad comes out of the shower naked covered with bubbles hearing the word "egg-nog". So Poof puts up the Super Not-Cosmo signal up in the air making Cosmo see it. So Cosmo goes sees what's the problem and sees that the destruction was the wished up villain, The Milkman. So Cosmo tries to defeat it but The Milkman goes wild. So Cosmo uses the materials he uses for the other bad things. So everyone adores him. But then, Cosmo goes home not wanting to be a superhero. But then when Wanda lets Cosmo change Poof's diaper, Cosmo changes it into a dragon and the dragon sends Timmy and Poof flying away up into the sky, making Wanda becoming Wanda Woman, flying away to catch Timmy and Poof!