Miss Dimmsdale is the first episode of Season 4. It is also the episode of the debut of Catman, because TV Legend Adam West makes his first Fairly Oddparents appearance as Catman.
Timmy is surprised to see Vicky working for Catman. It turns out that Vicky will stop at nothing to win the Miss Dimmsdale Pageant and its $10,000 first prize. She is bribing this judge and threatening another judge. She is even interfering with the competitors, and essentially getting rid of all the other contestants. When Timmy learns that his Mom’s and Dad’s dream is to win Miss Dimmsdale, he wishes that he were a judge so the contest can be fair. Who will win?
Timmy is at Adam West's magnificent mansion, the "Stately West Manor". He hopes to get an autograph from the actor who played "Catman". Timmy arrives and sees that Adam West is wearing his superhero costume. Timmy gives the photo of West to Catman and requests a signature. When Catman asks who it is for, Vicky appears suddenly causing Timmy to blurt out her name in surprise. hence, Adam West writes her name onto Timmy's photo. Vicky had been cleaning up Adam West's house for free. She also cleaned his cat-mobile and Cat Cave. She takes off in a hurry. Two orderlies appear with a needle and catching net, telling Mr. West that it was time to go "night night". He runs off while the orderlies sigh and unenthusiastically chase after him. Meanwhile, Timmy is left to ponder Vicky's strange and suspicious attitude.
Vicky is at Dimmsdale City Hall attempting to persuade the Mayor to vote for her for Miss Dimmsdale. He is reluctant at first, but when Vicky threatens to blackmail him with photographs of him from the 1970s in humiliatingly out of fashion clothes, he quickly gives in. Meanwhile, Timmy and his fairies are disguised as a window washer and his gear, they appear in the window behind Vicky and the Mayor, trying to figure out why Vicky is blackmailing him. Wanda points out to her godson that Adam West and the Mayor are both judges in the upcoming Ms. Dimmsdale-beauty pageant. Vicky must be trying to bribe her way into winning the title, and a $10,000-cash prize. The winner will also become the Mayor of Dimmsdale for a day. He must prevent Vicky from winning, because then she would be mayor... and even for just one day, she would bring disaster on everyone in the city.
Timmy wishes himself as a third judge in the pageant to help make sure that whoever ends up winning the competition wins it fair-and-square...and isn't Vicky. Wanda admits that she doesn't get why people make such a big deal about beauty pageants and questions why anyone would want to win one so badly anyway. It then cuts to Timmy's mom at the Turner house. Mrs. Turner explains that it's always been a dream of hers to win the Ms. Dimmsdale-beauty pageant "fair and square," and that she really wants to compete in (and hopefully win) this year's pageant. After Mrs. Turner reveals to her son that an old swimsuit of hers still fits (the swimsuit is revealed to be a bikini), Timmy's eye starts twitching. Then it turns out that his dad (who's wearing a glittery red speedo that's clearly too small for him) is planning to compete in the pageant as well--although Timmy points out that only women can compete in the pageant. After Timmy's parents drive off, he reminds himself that his parents have a chance since Vicky cannot bribe him with money. Vicky appears and instead tries to threaten Timmy by stapling him to the wall, but Catman appears and rescues Timmy briefly, before Vicky uses a leaf blower to pile a ton of trash of them both. She walks off laughing wickedly, but Catman knows the truth behind Vicky's scheme and he vows to make the pageant right...when it happens a week from now.
A week later, the pageant's being held at the Dimmadome. Aside from Vicky and Mrs. Turner, the contestants consist of A.J.'s Mom, Dolores-Day Crocker (Mr. Crocker's mother), and Geraldine Waxelplax. Timmy's one of the judges, his fairies appear as a glass and jug of water and give Timmy a wink who winks back. Vicky also gives the Mayor a wink, and he gives a nervous wink back. Chet Ubetcha is the emcee for the pageant, and introduces the contestants. First up is Mrs. Turner, who says she wants to Miss Dimmsdale for "all the wonderful things she can do as mayor for a day" (although her vision turns out to be pretty much the same as Vicky's, with all the men in the city enslaved). At the side of the stage, Mr. Turner is in a dress and trying to get into the pageant but security stops him. As Timmy's dad brings up the (quite arguable) point that men should be allowed to compete in beauty pageants just as much as women should, Adam West's orderlies appear and note that Mr. Turner is much crazier than Adam and chase him across the stage with a big needle while he screams very girlishly.
Vicky decides that her best hope of winning the competition is simply getting rid of the other contestants--she pulls a lever on the side of the stage, causing Mrs. Crocker, A.J.'s Mom, and Principal Waxelplax to fall down a trap door (Waxelplax almost climbs back up, but Mrs. Turner discreetly kicks her back down). Timmy's worried that Vicky is going to win without any competition, but Catman assures him that he "has a plan"...Catman and Timmy suddenly appear tied up in a rope suspended above a boiling pot of stadium hot dogs. Timmy remarks "THIS is your plan?", and Catman admits it was more of a "vague concept." Vicky is nearby and unleashes a rat onto the rope, who begins to gnaw on it. Timmy wonders where Cosmo and Wanda are. Wanda senses that Timmy is in trouble, but before they can raise their wands and wish him out of it, the Mayor picks them up and drinks from their cup form much to Cosmo's amusement.
The talent portion of the competition is going on, and Vicky is making sure that none of the other contestant's acts end without a horrible injury to whoever was on stage. Mr. Turner is on the sidelines, arguing that he is being discriminated against. He is about to be cornered by the orderlies, who give him a book that details the wrong of his actions as they try to capture him but Mrs. Turner (who was being propelled off the stage thanks to her sabotaged act and Vicky) collides right into them, and knocking Mr. Turner into a rope and causing him to get tied up and suspended in the air. His only relief that he is at least not suspended above a boiling pot of hot dogs before he escapes.
Timmy, who is still in the same situation as his dad (only with boiling hot dogs), asks Catman for a solution, or at least a way of getting rid of the foul smelling water. This gives Catman an idea, he has Timmy chew through a pack on his belt, but the pack spews pepper gas. Catman apologizes and says to chew the pack next to that one, this pack causes cat litter to pour into the pot just as the rope snaps. Timmy and Catman (and the rat that was chewing on the rope) fall harmlessly into the cat litter filled pot.
Timmy returns to judge, but Vicky is the only contestant left. She is about to be rewarded the prize-money and the key to the city. She brags that there is nobody else in a dress to challenge her. Mr. Turner falls from the catwalk above, and crashes into various costumes and items... which wins the various contests (i.e. swimsuit and talent contests) while he clumsily stumbles around the stage.
Catman is impressed that dad completed the entire pageant in one act. He tells Timmy that his dad "does' have it."
Mr. Turner wins the pageant as per what the judges vote, while the other contestants take out their anger on Vicky for her cheating skills by violently beating her up. Timmy is glad that Vicky won't be mayor for a day, but Cosmo then questions to Timmy what is the worse that his dad could do as mayor, causing Timmy to stare at the screen in silence due to the thought of the stuff that his dad could do as mayor. It then goes to the next day and it is shown that Mr. Turner has turned the city into his dictatorship, although the only person that seems to be affected is Sheldon Dinkleberg who Mr. Turner forces to endlessly turn a wheel and clean his statue. The episode ends with Timmy telling Catman his dad is not going to call him.