At CatDog’s house, Cat is working on his own flying machine that he plans to enter in Nearburg's upcoming “Invention Convention”; he calls it, a “Fly-Cycle”, and he is sure it will win him first prize. Dog is assisting Cat, and Cat instructs Dog to turn a knob (on the controls for a motor that’s temporary connected to the “Fly-Cycle’s” bike pedals to help Cat tighten a bolt) to the left (to make the motor turn slowly) on his signal; Cat puts his wrench into position and gives his signal for Dog to turn the knob. Unfortunately, Dog doesn’t know which direction is left, and (after trying a classic “Eeny, meeny, miny, moe” guess) turns the knob to the right by mistake; this causes the motor to turn fast instead instead of slow, which leads to Cat’s arm (which was of course holding the wrench) and then CatDog’s entire body getting wound around his “Fly-Cycle’s” bike pedals, which then flings CatDog around the “Fly-Cycle’s” back wheel, onto the fly cycle’s rotary wings, and finally into the kitchen where Cat’s mouth crashes into the light fixture. Winslow comes out of his mouse hole and asks cat (whom he mockingly refers to as “Einstein”) is he’s making a flying machine or “just a racket”; Cat frees his mouth (which is now stretched out from cusping part of the light fixture) and points out: “Dog here doesn’t know his left from his right; do you dog?” Dog agrees: “I guess not.” Winslow then mentions to Cat that it must be rough having to be attached to someone who’s not as smart as he is; both Cat and Winslow then look back in the kitchen and watch Dog attempting to eat one of his Dog biscuits, who attempts to chew it before putting it in his mouth and then smashing it over his head and eating the crumbs as they drop down from his head. Cat concurs with Winslow’s statement (“Oh, you’ll never know Winslow, you’ll never know”) and then begins to ponder up a way to make his brother smarter.
Later, at the kitchen table, Cat presents Dog (who’s licking crumbs off a plate in a rather messy matter) with a present; an excited Dog opens it and finds that it’s a collection of educational videotapes (titled “How To Learn Everything”). Cat explains that the videos will stimulate Dog’s brain and improve his mind; Dog asks Cat why he would want to improve his mind, and Cat sarcastically replies: “So that I don’t lose mine.” CatDog then goes into the living room, puts one of the videotapes into the VCR and begins watching the program; the program explains to Dog that “thinking is fun, it makes the brain happy” (Dog says “hi” to the smiling brain on the screen), and the program then gets right into sharpening up Dog’s math skills. Dog is drawn to the program and continues watching it into the night after Cat has fallen asleep next to him (which by then mentions that Mt. Everest is the world’s tallest mountain and then continues by getting into the subject of art). We then fast forward to the next morning, and we see CatDog at the kitchen table; Cat is reading his newspaper, and Dog seems to be fiddling with his food (he throws one of his dog biscuits aside, and picks up another and examines it closely); Cat frustratingly tells Dog not to play with his food, but Dog explains that he’s not “playing” but rather building a replica of the Great Pyramid of Cheops, which he mentions he learned about on those videotapes. Cat gladly states that he’s impressed. Later, as Cat continues working on his “Fly-Cycle”, we see that Dog is now helping Cat without struggling or making any mistakes; Cat complements Dog for a job well done and then asks him for one of the tools on his tool belt, Dog interrupts and assumes his brother is asking for a screwdriver, and he suggests (and at the same time retrieves from his tool belt) a Phillips-Head and mentions that it was invented by John Jacob Jingleheimer Phillips in 1732 (though this fact seems to be incorrect) before handing it to his brother and then proceeding to work on a calculator. Later that night, as CatDog are in bed and getting ready to go to sleep, Cat mentions it was a glorious day and like Dog smarter; Dod also mentions that he likes being smart and that he could perhaps be as smart as Cat one day. At that possibility, Cat laughs before muttering “no you won’t”, and then turns out the light and falls asleep. Dog on the other hand, rather than going to sleep, decides to get even smarter to make his brother even happier; he checks to make sure his brother is really sleeping (which he is) and then opens a secret trap door in his side of the bed and goes though it to a secret space under the bed that contains a small TV and VCR and the collection of “How To Learn Everything” videotapes. Dog puts one of the tapes in the VCR and stares at the screen with wide eyes; the program begins by mentioning (with accompanying visual aids) that a rectangle is made up of 4 90 degree angles, but Dog find this too easy and decides to fast forward to “get to the hard stuff”. As Dog speeds though the program, we hear the narrator mention Sir Isaac Newton’s first law of motion before proceeding into incomprehensible nonsense, and we see the visual aids mention (among other things) the irrational value of pi, Fermat's Last Theorem (which is incorrectly presented as “x2 + y2 = zn”), René Descartes, and Robert H. Goddard; and all the while, Dog stares at the screen and takes in every bit of knowledge the program presents.
We then fast forward to the next morning and see cat wake up; he yawns and stretches before being startled by something. We see that that that something is Dog, who’s brain has grown so large that it’s bulging out from within his head. Cat states to Dog that he startled him, and Dog rebuttals: “Sorry Cat; Cat - A domesticated feline from the latin ‘Felinius Caticus’. [that is actually not quite correct; the true biological name is ‘Felis Catus’]”. Cat however gets confused for a moment by that random statement of Dog’s, and he then takes a close look at Dog and strangely asks “Did you get a haircut or something?” Dog explains (while Cat pokes Dog’s enlarged head in awe) that he acquired more knowledge by watching all 632 videotapes 7 times; and Dog also mentions that he also discovered a new comet, sculpted, conducted an experiment on ‘contained nuclear fission’ (Dog holds up a snow globe with a small island inside that explodes), and improved cat’s “Fly-Cycle”. Cat however soon shockingly sees that “improved” is quite an understatement as Dog single handedly built a rocket ship on top of Cat’s invention, and Dog explains that with his “newly implemented design changes”, Cat’s propeller and wings are “really not necessary”. Winslow hops into the scene and mentions to Cat: “Looks to me like you’re the one who’s not necessary Cat”; Cat rebuttals nervously: “Oh, don’t be ridiculous; I-I-I’m still the brains behind this operation.” Dog then “flexes” his brain (as if one were to flex his chest muscles), and Cat looks onward with slight jealousy. Later, we find CatDog working on “Cat’s” invention (and Winslow looking onward while sitting on a nearby toolbox), but Dog is now doing most of the work and Cat is assisting; Dog asks Cat (whom he now refers to as “Felinius”) to hand him a metric socket wrench. But Cat (who’s front teeth have become suspiciously enlarged) suspiciously gets confused, gets distracted by a hairbrush (which he uses to brush his hair for a brief moment) and gets a headache while trying to remember what Dog said before asking dog: “Doh, what an I looking for again?” Winslow then tells Cat: “Hey, I get it: Dog’s got a brain vacuum going. He’s sucking knowledge from everywhere… Including you.” Cat again tells Winslow to not be ridiculous; but he immediately feels something strange (and we notice his front teeth getting even larger) as Dog begins reading a stack of books as breakneck speed and causes his brain to grow even bigger! Cat realizes in horror that Winslow has a point: As Dog increases his own intelligence, Cat’s intelligence drops; and as Cat’s realizes this, his own brain suddenly (and literally) shrinks to the point of becoming seriously retarded (and his speech becomes slurred and comparable to that of Lube’s)! Cat immediately attempts to reverse this by watching one of the “How To Learn Everything” videotapes; but Cat’s serious retardation has compromised his motor skills and he’s unable to put the tape into the VCR (and he smashes it to pieces as he tries in vain to put it in).
Later, at the “Invention Convention”, Randolph Grant (who is the convention’s judge) presents 1st prize to Cat for “his” marvelous invention (Dog doesn’t appear to mind Cat getting the credit, although the mentally impaired Cat doesn’t seem to be trying), and asks Cat to explain how it works. But all the only thing the mentally impaired Cat can think to say is: “It works good-ha… it flies with.. fffastness of being in the air.. part when it goes.. Whooo! (and then makes airplane noises and puts out his arms as if they were wings)”. Dog then relieves Cat and steps in to explain (and he hands his brother a chocolate ice cream cone to keep him occupied); Dog then explains: “The basically-stratuospherous is aeronautically sound upper altitude vehicle, which uses atomic fuel and a hydraulical system to attain maximum velocity.” Randolph rebuttals with one of his trademark “And I love it!” takes, and he then asks Cat if there’s anything he’d like to add. But all Cat can think to say is: “Umm… I got Chocolate (saying this as he holds up his Ice Cream cone and staffs it into his face)!” Cat’s behavior prompts the bystanders to laugh at Cat, and this hurts Cat feelings; a hurt Cat then tries to defend his ego to the laughing bystanders (“Wha-? What funny with laughing!? You think I smart not!? I’m smart I’m sm-”), but Cat then gets distracted by a big red button with a flashing light inside Dog’s rocket ship, and goes inside (though a doggie door) to push it. Dog (still outside) immediately tries to stop his brother (“No, no feline! Do not engage that button!”), but his intervention is too little too late: Cat pushes the button and this starts up Dog’s rocket ship, which then blasts off out though the roof of the convention center, leaving Randolph and the bystanders charred (Randolph also crumbles to a pile of ashes and gives another one of his trademark “I love it!” takes). Dog’s rocket ship charges into outer space as Dog is dragged along, but Dog scrambles inside after his brother and struggles his way to a lever which stops the rocket’s engines and pulls it; Dog then takes the controls of his ship. Cat then approaches his brother and protests: “They all go ha-ha with laughing at me. Making fun! They make me spill my ice cream, all gone.” Dog replies: “Well, be that as it may. Your actions were rash and injudicious; one really shouldn’t play with technology beyond one’s comprehension!” A confused Cat replies “Wha- Huh?”, and Dog rebuttals “Never mind, (sighs) you wouldn’t understand.” Hearing that however prompts Cat to snap: “You! You-di- did this to me Bow-Wow Person! You make the smart go Bye-Bye! I WANT SOME MORE SMART BACK. GIVE ME BACK SMARTS!” Cat then grabs and squeezes Dog’s head, which forces the intelligence out of his brain, though CatDog’s body, and into Cat’s brain; now Cat’s head is bulging like Dog’s was and Dog’s head is shrunken like Cat’s was; Cat tests his reinvigorated mind by stating “The Circumference equals pi radius squared” (which is incorrect; it’s area, not circumference, that equals “pi radius squared”).
Cat then rubs it in Dog’s face by stating “Who’s the smart one now?” But a now retarded Dog protests: “Hey! I using that brainy!” Dog then grabs Cat’s head and squeezes it (much like Cat did just before), and the intelligence then travels back though CatDog’s body and back into Dog’s brain. Dog then tests his recovered intelligence by stating: “The Cartesian principle states: ‘I think, therefore I am’.” Both brothers then begin fighting over the intelligence and resorting to various methods to take it from the other; and with no one at the controls, Dog’s rocket ship flies across the universe out of control and bump into obstacles. Eventually, while Cat has the intelligence and Dog is trying to recover it for himself, Dog fires his brother out of a cannon and both brothers heads bounce (like a rubber ball) off the walls of Dog’s ship multiple times; and when Cat and Dog finally come to rest on the floor, they find that it put them back to the way they were. As the ship starts hurdling at top speed back toward Earth, both brothers then make up; Cat promises Dog that he’ll handle the brainwork from now on, and Dog agrees and mentions that someone needs to fly Dog’s rocket ship. But as Cat steps up to the controls and sees the ship hurdling toward Earth, he realizes that now neither he nor his brother have the intelligence to pilot Dog’s rocket ship (Cat: “Uh-Oh!”)
The out of control ship then charges straight into Earth’s atmosphere and begins burning up like a meteor! Both brothers grab each other and scream in sheer fright as their vehicle breaks apart and guarantees a certain and awful death to both brothers!!! But in a god blessed miracle, both brothers suddenly emerge from the flames unscathed, riding on Cat’s original “Fly-Cycle” mid-air. A heavily relieved Cat excitingly points out that his original invention works, and a heavily relieved Dog complements his brother and states that he’s a genius (Cat replies: “Ain’t it the truth!”). Dog then asks how to land Cat’s “Fly-Cycle”, but Cat realizes in more horror that he forgot about the landing, and tells Dog: “Keep peddling dog, Just.. Keep.. Peddling!” We then see CatDog flying above the ocean into the sunset and Cat wines in horror and again tells Dog to keep peddling; the episode then ends there.