Codename: Kids Next Door - Season 3 (2004)

Numbuh Five encounters a deadly school situated beneath the ground while she is out attempting to locate her missing classmate Leona.

In "Operation: B.U.T.T. (Blackmail Uncovers Titanic Tush)", when the KND force Numbuh 1 to take time off at the beach, they unwittingly set him up for exposure in the most embarrassing way possible. In "Operation: T.R.A.I.N.I.N.G. (Tiny Recruits Ambushed In Nefarious Invasion Need Guts)", at the KND Arctic training base, a handful of new KND trainees, including Numbuh 2's little brother, Tommy, are supposed to receive their training via simulations, but soon they're up against something that is no simulation whatsoever.

In "Operation: A.R.C.H.I.V.E. (Ancient Recorded Children's History Is Very Enlightening)", the tale of how the animosity between children and adults got started is revealed, a la "The Second Renaissance". In "Operation: S.L.U.M.B.E.R. (Stupid Little Undercover Mission Becomes Exciting Romp)", Numbuh 86 is holding a girls-only slumber party... and nothing will keep Numbuh 4 from attending, even if he has to disguise himself as a girl.

In "Operation: P.I.N.K.-E.Y.E. (Private Investigator's New Kase Extra Yucky Epidemic)", Numbuh 2 is now playing role of detective at his school and soon he has a case on his hands: an epidemic of pink eye. Numbuh 2 decides to investigate and find out who it is that is infecting the kids with the disease, despite a hindrance from his pre-KND days partner, the new hall monitor Joe Balooka. In "Operation: K.A.S.T.L.E. (Kuki And Sister Torpedo Loathsome Engagement)", on a trip to a Rainbow Monkey-themed amusement, Numbuh 3 and her baby sister Mushi are having the time of ...

In "Operation: C.A.K.E.D.-T.H.R.E.E. (Commandos Attempted Kapturing Enemy's Dessert - They Have Real Extreme Eggravations)", it's the Delightful Children From Down the Lane'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 with real eggs lays an egg and they have to decide if the cake is really that worth it. In "Operation: L.O.C.K.D.O.W.N. (Lurking Otherworldly Childhood Kalamity Delivers Ouchies When Naughty)", late one night, Numbuh One returns to the ...

In "Operation: G.R.A.D.U.A.T.E.S. (Gargantuan Ray's Advance Decimates Unprepared And Terrified Escaping Soldiers)", Numbuh 2's kid brother, Tommy, is inducted into the Kids Next Door. Unbeknownst to them, however, Father and the Delightful Children From Down the Lane are preparing for a major all-out war...

In "Operation: H.U.G.S. (Humongously Unwieldly Gorilla Showdown)", Numbuh 4's clear dislike of everything related to Rainbow Monkeys is only worsened when he winds up on Rainbow Monkey Island and meets a GIANT Rainbow Monkey Kong. In "Operation: J.E.W.E.L.S. (Juvenile Escapes With Extremely Luscious Sweet)", Numbuh 5 heads to the Suhgar Desert to retrieve a stolen candy known as the Blurpleberry Supreme. But she quickly discovers that she is not the only one craving the candy; an old rival of hers has plans to use to unlock a candy pharaoh's tomb.

In "Operation: T.R.I.C.K.Y. (Trivial Rival Instigates Candy Krazy Yearning)", it's trick-or-treat night, and Numbuh 4 sets off on his own to prove he can get more candy than his teammates - without even wearing a costume. But he only receives a single piece of butterscotch, and that ends up being stolen by Stickybeard and his candy pirates, who are taking trick-or-treat candy from neighborhood kids. Furious, Numbuh 4 races after them to retrieve his candy. At this rate, how will his candy count ever top that of his friends? In "Operation: U.N.C.O.O.L. (Undead's ...

In "Operation: P.R.E.S.I.D.E.N.T. (Protection Requires Extreme Skill Involving Democratically Elected Notable's Transportation)", the Fourth Grade President is determined to help ease problems at school that kids have to endure. However, he is under attack from the Delightful Children and their minions, who are out to stop him, so the Kids Next Door are sent in to protect him. In "Operation: H.O.S.P.I.T.A.L. (Hurt Operative Safely Protected In Totally Antiseptic Location)", a significant operative is injured and hospitalized during a tough mission and the Kids Next ...

In "Operation: S.P.R.O.U.T. (Sickening Produce Removal Operation Ultra Tricky)", Numbuh 4 is horrified when he accidentally eats a brussels sprout at his family dinner table. His teammates rush to his aid, and it is decided that Numbuh 1, Numbuh 2 and Numbuh 5 must go in and retrieve the offending vegetable. In "Operation: H.O.U.N.D. (Homework Obliterated Using Nefarious Dog)", Numbuh 5 is chased on the way to school by a giant, ferocious dog that steals and eats her homework. She is convinced that the dog was the pet of a rival classmate, Valerie, because she saw it ...