The Kids Next Door attempt to stop a birthday party for their arch-enemies, the Delightful Children from Down the Lane. The task is made complicated by the presence of the Big Badolescent, a girl who grows alarmingly in size and strength when she does not get her way.
Kenny and Chimpy are hired by Professor Triple Extra Large to do chores in his horrible disease storage laboratory, and everyone knows that chimps just aren't careful.
When the villainous Mr. Wink and Mr. Fibb extend the adult swim time in the neighborhood pool, the Kids Next Door are sent a red alert to stop them. Numbuh 1 suggests employing the Kid-A-Pault, a Kids Next Door weapon to put an end to this tyranny...but their plan fails, leaving them to find other means of battling Mr. Wink and Mr. Fibb.
Numbuh 4 forces the other operatives to build a "clam cannon" when Numbuh 1 leaves.
The group catches wind of some ice cream men who refuse to give ice cream to children, so they interrogate them and get the password to their ice cream factory, only to be in for a major surprise from the Delightful Children from Down the Lane, because the ice cream that they take turns into a monster that tries to eat them, but eventually gets defeated by a heater that was turned on by Numbuh 3.
The hamsters that power Sector V's weapons suddenly decide to go on vacation, leaving the Treehouse powerless! Meanwhile, the Delightful Children from Down the Lane looks for villains to attack Sector V, so they send an old lady named Gramma Stuffum, who is fixated on fattening kids, to Sector V's powerless HQ.
The Kids Next Door find a new enemy in the dental hygiene-obsessed vigilante, Knightbrace, after he attacks Numbuh 3 on the way back from a trip to the candy store.
Captain Stickybeard and his Candy Pirate crew steal Sector V's candy, including Numbuh 5's secret stash. Numbuh 5 does not want her candy stash to be taken, so she boards Stickybeard's pirate ship to retrieve it. The KND have to rescue her and the candy too.
An adult named Lasso Lass (who keeps acting like a kid) wants to help Sector V defeat Mr. Wink and Mr. Fibb.
When turnips are found everywhere in Sector V's treehouse, they go to the source: a giant turnip, to defeat it.
After Numbuh 2 beats a mini-golf champion at mini-golf, the golfer shrinks Numbuh 2, and many sights from around the world.
When his father brings Numbuh 4 to work for "Bring Your Daughter to Work Day", Numbuh 4 discovers his father's boss plans to send him and all the daughters of his co-workers to Pluto.
A fellow operative, Numbuh 30C, is sent to help Sector V stop a villain from using a weather machine to make no more snow days for school. But is there more to this mysterious operative than meets the eye?
The Delightful Children from Down the Lane attack Sector V's headquarters with an infestation of hair-eating lice.
Numbuh 1 has a secret girlfriend who he often neglects because of his Kids Next Door responsibilities, forcing her to use a boyfriend helmet to mind-control Numbuh 1. If the helmet stays on for too long, it will start to merge with Numbuh 1's head and stay on forever.
All of the teenagers in Sector V's hometown have formed a place called The Point, and Numbuh 1 suspects that they are helping the adults.
A fly finds its way into Sector V's headquarters.
A lost baby skunk interferes with a mission to rescue brainwashed campers.
A villainous half-man, half-baby named Mr. B gives the Kids Next Door, a television series of their own.
Two parental villains are stupefying KND operatives around the world; an operative named Chad (Numbuh 274) enlists the help of Sector V.
Numbuh 2's little brother, Tommy (who is shunned by Sector V), joins forces with a villain, Common Cold.
Sector V tries to destroy all the pianos in a truck with a hamster that acts as Numbuh 4's replacement.
Sector V is put into a "kids zoo" and must unite with the Delightful Children from Down the Lane and get all the other children out of their cages before lunch time to escape being fed to the zoo's cannibal bully.
Numbuh 5 tries to keep the treehouse quiet, so Numbuh 1 can sleep.
The boss of Rainbow Monkeys Inc. uses Numbuh 3 to find real Rainbow Monkeys for him.
The frustrated Delightful Children from Down the Lane turn to their Father for help destroying Sector V. Numbuh 1 is turned into an adult, the treehouse is destroyed, and their faith is shattered; Sector V is forced into a showdown with their most dangerous foe yet.
The KND's soda pop is sought out by an evil industrialist. The legal age for drinking soda has been changed to Everyone 13+. Numbuh 2 is caught selling illegal soda at a local bar and discovers a conspiracy to bottle kids.
Numbuh 4 is mistaken for a cat by an old lady after being stuffed in a kitty costume from his dispute with Numbuh 3.
The KND and nearly every kid in town are invited to a dance at the DCFDTL's mansion. However, it was actually a trap, all the party guests (except Numbuh 1 and Lizzie) are "delightfulized" like the DCFDTL.
Count Spankulot joins the KND and turns from his evil ways.
Numbuhs 2 and 1 try to find out about Cree's B.R.A. (Battle Ready Armor).
Numbuh 2's grandmother joins forces with her friends to locate a pudding supply, which was trapped between the surface of the treehouse.
Numbuh 3 is sent on a mission for her birthday: to get a fast food meal. The restaurant is later revealed to actually be for sharks, with kids being murdered for food.
Numbuh 4 tries to sneak into an R-rated movie to find it is a secret villain meeting.
Numbuh 1's dad is grabbed by a fishing line along with other dads on the lake, and pulled up to some kid's house above the water. He decides that Numbuh 1's dad is his new dad, so Numbuh 1 battles it out with the sousaphone-playing dork for his father.
The KND investigate why people are getting mustaches. They end up showdowning the "head mustache", but they're in for a surprise of who's to blame.
Numbuh 2 is turned into a teenager when an experiment goes horribly wrong, but gets smooth with Numbuh 5's older sister.
Numbuh 5 is kidnapped and sent to a temple to find a mystical flavor of ice-cream known as "The Fourth Flavor" for the DCFDTL. She dreams to have a chance at tasting the long-lost flavor herself, for only those with pure taste buds may taste it.
The KND try to find an escaped moonbase prisoner at the DCFDTL's mansion, but the boys are brought down with Numbuh 86's yelling and complaining.
When Sector V (except Numbuh 4) assists Chubbo's funeral, the ghost arrives at night, kidnapping Numbuh 3 and keeping her with all the past dead hamsters powering the treehouse's core.
While the others have their day off, Numbuh 1 tries to rescue the ten-year-old accepted into college. He finds out that it was his own brain the Professor XXXL wanted: a test subject to his snow cones, since Numbuh 1 is immune to brain freeze.
A new cheesy restaurant opens, but all the cheese is stolen. When Numbuh 2 tries to use his own cheese, he and Numbuh 4 are captured by cheese ninjas.
The KND each give an account of what happened to an ordinary package.
Numbuh 1's underwear is attacking him after finding out how careless children are with underwear.
After a spaceship crash caused by Numbuh 3's sister, the KND search an abandoned prisoner transport and discover that they're not alone.
The KND take it to the skies to stop the DCFDTL's birthday cake.
The KND try to close down a coffee drilling rig with a surprising ally, Lenny, one of the DCFDTL.
A king forces Numbuh 3 to marry him, but she agrees because she thinks they're pretending. Meanwhile, Numbuh 4 will fight King Sandy for Numbuh 3.
Numbuh 3 is followed by the ITFBTM (Interesting Twins from Beneath the Mountain), the cousins of the DCFDTL, when she goes to Japan, so they can infiltrate the Japanese KND headquarters.
Numbuh 2 is shot out of the sky by another pilot countless times, who he thinks is a threat.
Numbuh 86 arrives at the KND treehouse and captures Numbuhs 2, 3, 4, and 5 for decommissioning. Numbuh 1, having previously eluded Numbuh 86, immediately sets out to determine who's ordering the wrongful decommissioning of scores of KND operatives.
Numbuh 4 learns he is to be sent to a boarding school – but he is not worried, as he's always escaped from them before. However, he then learns that the school is being run by an evil kid called "Madame Margaret", a girl who is getting high-tech aid from none other than her future self. Madame Margaret's abominable plan is to create a twisted utopia where girls rule the world, using a demonic weapon called the girlifying ray that can turn anything feminine. The team does not have much chance to stop this until they receive aid from Numbuh 4's own future self. Now the team must defeat her and save the future.
The KND crashland into a sea of asparagus, and find out that they have more to worry about than staying afloat.
Lizzie Devine takes over the KND, and puts herself in Numbuh 1's place.
Numbuh 1 discovers an island paradise populated by kids. Numbuh 1 finds a perfect island, with much candy, fun and no adults. However, he deduces something unusual is happening and has to do with Chester's Happy Headband.
The Six-Gum Gang is stealing everyone's homework on a school bus for the DCFDTL.
The DCFDTL kidnap the team's classmate, a nerdy, spit-talking girl named Leaky-Leona and force her to lead them to the dark underbellies of the school. Alerted by Numbuh 5, the team follows them, and find themselves in an ancient school, laden with deadly booby traps. Avoiding them all, the team finds Leaky-Leona, strangely aged to an old woman, who leads them to the mythical Fountain of Youth. The KND are amazed at the prospect of remaining ten-years-old forever.
The DCFDTL plants Numbuh 1 from his swim trunks and get photos of his disproportionately huge buttocks. They black mail him with them.
Tommy, Sonia, and Lee find that the training simulations in the Arctic Base are real.
Numbuh 86 is having a top-secret girls-only mission. Numbuh 4 is willing to find out what the mission is all about even if it means having to put on a little make-up. It turns out to only be a slumber party, but then it turns into a real mission.
An archive is shown of the origin and story creation of adults, and their rebellion of children. Numbuh 1 narrates on how adults were created, how they took control, and families were made.
Numbuh 2 investigates a pink eye outbreak in Gallagher Elementary in a noir style. An epidemic of conjunctivitis (pink-eye) has taken several victims. Numbuh 2 must investigate if the cases are coincidental or if a certain nurse is causing them.
Numbuh 3 is forced to be married to King Sandy (again) when she is at a Rainbow Monkey theme park, but the others will not believe her.
It is the DCFDTL's birthday once again, and as always, the KND go to rob their nemeses of their ever-delicious birthday cake. However, their plan to neutralize them by egging them goes wrong as chicks hatch from every single egg.
Numbuh 5 tries to find an intruder in the KND treehouse. Numbuh 1 orders a complete lock-down of the treehouse but the enemy is already inside, and one by one the operatives are getting spanked. In the end, the KND start spanking!
Numbuh 5 journeys to the exotic Al-Shugar Desert to recover her stolen candy, the Blurpleberry Supreme, and discovers she's not the only one searching for the powerful, mystical candy.
Numbuh 4's disgust at anything Rainbow Monkey only increases when he finds himself trapped on Rainbow Monkey Island with a gargantuan, monstrous Rainbow Monkey Kong. He tries to teach it to be a dangerous monster, but all it can do is love.
The Code Module is recovered by Sector V in time for Tommy to graduate. However, the information inside of it is used by Father to turn every single operative into an animal, leaving Tommy the last one who's not transformed into an animal since he removed his DNA from the Code Module in order to save the KND.
The KND try to find Numbuh 78 in a treehouse infested with Nerd Zombies.
Numbuh 4 tries to get his candy back from Stickybeard on Halloween.
The KND try to get the Fourth Grade Class President to his Town Council meetings safely.
An important operative suffers an accident on a dangerous mission and is sent to the hospital, but one ex-KND member is out to scramblify his brain, and Sector V must make sure he is safe.
Numbuh 4 accidentally eats a brussels sprout, sending the rest of the KND on an emergency Fantastic Voyage to stop the dreaded vegetable from being digested.
Numbuh 5 comes face to face with a vicious dog who is always eating her homework.
Mr. Boss, Knightbrace, Mr. Wink & Mr. Fibb, and the Crazy Old Cat Lady are taking over the treehouse of Sector V, and the Toiletnator tries to get rid of the KND for good, or so he thinks.
Numbuhs 2 and 5 travel through the school jungle gym to help find the First Grade's missing pet bunny, Mr. Fluffalupagus, from Heinrich Von Marzipan, who kidnapped him and plans on making chocolate bunnies from real bunnies by dipping them into the chocolate volcano.
Numbuh 3's family are invited to Numbuh 2's house, where Mrs. Gilligan is hoping to get a promotion out of this. It is later revealed that the Rainbow Monkey is stabbed by a fork.
Gramma Stuffum forces the kids to eat her food.
Numbuh 4 tries to protect chicken nugget mines from the DCFDTL.
The KND try to protect the Macaroni Museum of Art from being ransacked, with the worst KND operative ever, Marty Sullivan, (aka Numbuh 13), on their side.
Numbuh 4's new pool is actually a portal to an alternate version of the KND Universe where their counterparts known as the DNK (Destructively Nefarious Kids) are evil. The kids do all the adults' job whereas the adults sit around and play video games. While swimming in the pool, Lizzie is captured by an evil opposite of herself, Eizzil Enived (Lizzie's name backwards), and Nigel follows the captor back to her home universe.
The KND tube race to get the DCFDTL's delicious birthday cake.
Numbuh 2's mom has to go out, so she finds Cree to babysit Tommy and him.
The KND try to stop a mysterious being from collecting all the Rainbow Monkeys in the world-- including Numbuh 3's beloved ones.
Numbuh 4 must choose between his job as a KND operative or be a bully fighter.
Numbuh 5 tries to stop Heinrich, now a chocolate monster (recapping the aftermath of "Operation: R.A.B.B.I.T."), from destroying her friends.
The KND have run out of Rainbow Munchies, their favorite cereal, so they send out tennis-ball probes to find a box. They find it in Aisle Number 60-teen at the Supervillains Supermarket & Deli, but it is the last one the store has, and it is as popular with the bad guys as it is with the KND!
Lizzie feels that Nigel works too much during lunch, so she forces him to have lunch with her, but he cannot work. Meanwhile, a group of lunch thieves and their leader Robin Food break into the cafeteria and start stealing everybody's lunches, including Lizzie and Numbuh 1's.
The KND try to rescue a boy from a monster in the closet.
Numbuh 1 battles a group of snake ties with an adult against them.
Jimmy Nixon McGarfield (the fourth-grade president) forces the other kids back into school on a first snow day for a special assembly after Numbuh 1 is too sick to play.
Maurice, a member of the Kids Next Door is decommissioned. Numbuh 5 is saddened by it, and suggests that they monitor Maurice to make sure the teenagers do not recruit him.
Numbuh 3 stars in a romantic musical as the lead girl, but when Numbuh 4 interrupts the play, it becomes a real war on stage between the DCFDTL and the KND.
Numbuh 4 tries to battle it out with an evil adult in his couch.
Numbuh 4 tries to battle against the Dodgeball Wizard for his rank.
Numbuh 1 and Sector V are on Rainbow Monkey Island trying to take "The Code" from the Delightful Children.
The KND try to save Christmas when the DCFDTL frame them for the theft of a gift-creating contraption called the "REINDEER System" created by Santa.
The KND are up against more than they bargained for when they try to prevent the DCFDTL for dashing the school elections, especially when the situation involves 8th graders.
The KND go to rescue babies from the hospital to protect them from becoming automatic adults. Numbuh 5 thinks the others are insane and tries to bring them back, but the babies themselves have other plans.
Tommy embarks on a journey with a cowardly cleanliness-fearing captain in the bath waters.
Numbuhs 2 and 4 travel to a certain place in the treehouse to give Numbuh 3's goldfish a proper funeral, while Numbuhs 1 and 5 try to win her a new one from a rigged carnival game.
Numbuhs 2 and 4 try to escape from an island inhabited by bully monsters.
Numbuh 1 tries to flee from a doctor who wants to cure his moosebumps.
Numbuh 4 uncovers a game in which priceless vases are broken.
The KND try to close up a virus being spread in a KND undersea laboratory.
Numbuh 5 tries to save her sister Cree from a contagious disease, that the KND have made in revenge for creating chicken pox.
The KND try to make a present for the Global KND anniversary.
Numbuhs 2 and 3 try to guide a plane full of hamsters. Meanwhile, Lizzie is jealous of a girl Numbuh 1 is hanging out with, and races over to try to keep Nigel from "dating" her.
Once again, a special birthday cake is being made for the Delightful Children from Down the Lane. The KND take a trip to the Alamode where tour guide Numbuh 50 Million B.C. tells them about the 1800s KND operatives who were determined to steal the Annoyingly Cute Triplets Who Lived Upon the Hill's Birthday Cake, a delicious cake made by their mother. However, in their attempt to get the recipe, an ice cream trap was set off, freezing over 5000 KND operatives. It took 10 years to thaw them out, and all were decommissioned since they were technically too old to be KND. All were found except Numbuh 19th Century, the operative sent in to get the recipe and set off the trap, until the current KND recently discovered him. After being thawed out, he's confused by the new modern era, especially with the fact there are now girls in the KND.
Numbuh 1, Numbuh 83, and Numbuh 84 try to save Numbuh 86's brother, Shaunie, from getting a haircut from his father. Unfortunately, they end up in combat with Shaunie's dad, who is none other than Mr. Boss.
A boy named Bobby tries to get through a training program with flying colors.
Numbuh 3's sister, Mushi, tries to get revenge on Numbuh 2 after being grounded for life for transferring Count Spankulot's power onto her Rainbow Monkey.
A clown tries to get Numbuh 2 as he plays many jokes.
Numbuh 3 is cold, so she turns up the heat even though she is not allowed by her father. It then gets very warm that the KND have to turn down the heating before Numbuh 3's house explodes. Meanwhile, Numbuh 4 watches over Mr. Sanban.
Numbuh 4 releases Mr. Boss, Stickybeard, Count Spankulot, and Soccer Mom from their cells. At his home he gives them sodas which he tricks them into thinking that they were poisoned, and tells them that he'll give them the antidote if they beat his dad in a bowling tournament.
Heinrich comes back, but this time needs to be saved by Numbuh 5 as she recruits Stickybeard and his band of candy pirates to help her rescue Heinrich from Black John Licorice and his pirates.
Numbuh 3 takes her "My First Rainbow Monkey" to a Rainbow Monkey Retirement Home, but it seems to be more than what it appears to her and Numbuh 5.
Every year, the KND choose someone to be "IT" which involves a game of tag to choose the next Supreme Leader, so Numbuh 362 sets up the game after she decides to resign due to being tired of the job. However, when Numbuh 2 accidentally tags Father, he becomes Supreme Leader. Numbuh 1 and Numbuh 362 then must stop him before he wipes out the entire KND using broccoli.
In the sooper triple gihoogest Codename: Kids Next Door adventure ever, an evil more eviller than Father threatens to turn both kids and adults into tapioca-eating, hideously wrinklified Senior Citizombies. To fight this menace, the Kids Next Door are forced to recommission their greatest operative ever: Numbuh Zero! Join Numbuhs One through Five and the rest of KND Global Command as they battle alongside their bygone hero to fight for not only kids...but the world!
When a kid-friendly senator receives a funding of approximately eleventy-billion dollars, he uses it to build an army of Safety-Bots, to make the world a safe place for children. However, the robots grow more and more extreme in their actions, eventually planning to eliminate adults, and cover the Earth in bubble wrap.
Sector V attempts to sabotage the Villain's Choice Awards.
When Numbuh 1 is taken to England, someone gives him a book, resulting in Numbuh 1 getting followed by 3 kids.
While the team is off on their recess-rescuing mission, the hamsters are attacked and captured by the Sinister Felines from Atop the Litterbox, but end up battling the Hamsters Next Door.
When salad oil is discovered in the school playground, Numbuh 1 must find a way to save recess, while still keeping a promise to Lizzie.
Numbuh 1 wakes up to discover that he is the president of the United States in an alternate dimension, who is about to sign the Bill of No Rights for Kids.
Numbuh 2 attempts to deliver the fourth grade president's message.
Amerigo Vespinaccio tries to spread spinach throughout the school, and Sector V must stop him.
Numbuh 20,000 and his Squid Squad work with Sector V to destroy the bridge leading into Le Sissie, a store in the mall that sells horrible back-to-school clothes for kids.
Numbuhs 2, 3, and 6 are tricked and must get a truckload of soda to a girl's birthday party and keep Mr. Fizz and Lieutenant Seltzer from getting the soda.
Tommy loves Numbuh 2's cruddy, old tricycle but gets laughed at when the other kids see him riding it. Using his 2x4 technology expertise, Tommy rebuilds it into the "Best Bike in the Whole World", but the bike turns evil trying to impress Numbuh 2.
With Father away at Saratoga Springs for the day on orders from his doctor, the DCFDTL invite Cree and the teenagers to their mansion to plan a new strategy against the Kids Next Door, but instead, the teenagers turn it into a wild house party, leaving the DCFDTL to call Sector V for help.
When Gallagher Elementary students are being arrested by the School Safety Patrol for crimes they are envisioned to commit, including detective Numbuh 2, leaving Numbuh 3 to investigate a psychic member of the School Safety Patrol while trying to finish her social studies homework.
Numbuhs 3 and 4 are launched into space to break the "Ridiculous" space barrier, but black out in mid-flight and wake up on a world ruled by anthropomorphic, talking Rainbow Monkeys.
Numbuh 5 goes into the Haunted Doghouse to get Sector V's cinder block back, but later comes out with different results.
Sector V sends Numbuh 2 into hiding at an Amish sector to his extreme dismay.
This episode illustrates a day at the annual kids' 2x4 tech science fair. Numbuh 2 is present, shoving his "I Can't Believe It's Not Booger" product down the judges' throats.
Lizzie has always had to compete with the Kids Next Door for Nigel's attention, and she thinks Nigel has found a new girlfriend.
Heinrich uses a ritual involving sacred golden caramels to take away the qualities the Sector V operatives value the most (Numbuh 1's leadership, Numbuh 2's intellect, Numbuh 3's giddiness, Numbuh 4's toughness, and Numbuh 5's coolness). Numbuh 5 eventually teaches Heinrich that he needs to share his candy to revert to his original form, she is then seen leaving with a young blonde girl.
Adults send Numbuh 4's family to the Moon to colonize it. However, Sector V diverts the colony to Hollywood, where they stage a fake colonization, tricking the Beetles family and the adults at mission control to prevent them from discovering the KND Moonbase.
The KND and the Teens are about to sign the "You don't mess with us-We don't mess with you" Kid-Teen treaty. It is going to be signed by Numbuh 8000 (KND and the Teens leader), but it turns out to be a trap for the KND, making Numbuhs 1 and 274 set out to prevent it after being falsely convicted by the KND.
Worlds collide when Billy accidentally steps into the Delightful Children's Delightfulization chamber with Grim's scythe and emerges as a hideous cross between himself, Grim, and the Delightful Children! Soon, the KND are called in to stop this Delightful Reaper's rampage across the country as it grows bigger and bigger, adding more and more children to itself to make the perfect child! With the KND leadership in a shambles, Mandy takes over the organization to fight this creature -- but may have ulterior motives in commanding her own army!
In a series of interviews with the KND after they're all grown up, the former operatives are temporarily brought out of their decommissioned haze to discuss what happened during their very last mission with Numbuh One -- the one where he disappeared and was never heard from again! It all started with a routine mission to get the Delightful Children's birthday cake, but when a mysterious boy steals it instead he makes it available to whoever wants it -- IF they can solve his 'simple' scavenger hunt first. Soon it's a mad, mad, mad, mad chase around the world as the KND, their friends, and virtually all of their enemies compete to win the yummiest cake ever while Nigel Uno is faced with the most difficult choice of his life: the KND or his friends. And the answer is out of this world.
