Kim rushes into school desperately attempting to get her paper printed and make it to class on time. She doesn't make it, and gets caught and given detention by Mr. Barkin. After going home with the bad news, she gets a call from Wade that sends her on a mission to investigate the theft of a tiny "robot tick" from a Professor Acari. A security camera tape shows the thief; a bit later, Wade identifies her as Shego, a criminal wanted in eleven countries.

After Kim's first detention session abruptly ends when Mr. Barkin mistakes Rufus for a mutant escapee from the science lab and evacuates the room, Team Possible pursues a lead that takes them to Dr. Drakken's Caribbean island lair. After getting captured, escaping from a SharkPool DeathTrap, and making their way through a fight that seriously damages the lair, they return home.

Back in detention, one of the others tells Kim she has a "zit" on her nose; in fact, it's the explosive "nano-tick" Drakken created from the stolen robot. The situation comes to a head when Drakken and Shego track down the device, ready to take it back if they have to take Kim's nose along with it.

With some help from her detention pals, Kim defeats Shego and Ron uses Dialo Sauce to remove the tick allowing Kim to use it to destroy Drakken's hovercraft in the first (of what will turn out to be many) defeats at her hands. Kim then returns to detention with a newfound respect for its' inhabitants, who fight over the chance to have her paint their nails.

!!This episode provides examples of:
* AssKicksYou: Shego's final defeat comes when Big Mike sits on her.
* CharacterizationMarchesOn: Although not quite there yet, Drakken & Shego are getting close to the personalities they will later be known for.
* ChekhovsGun: The elastic constricting lipstick that Ron tests out ends up helping Kim take care of Drakken's sharks.
* TheCloudCuckoolanderWasRight: After Vinnie tells him that "cheerleaders don't get zits" Junior correctly suspects the thing on Kim's nose is the nano-tick.
* DidIJustSayThatOutLoud: Actually Drakken didn't know he did until Shego points it out to him.
* FlashbackCut: Another to Ron's time at [[SummerCampy Camp Wannaweep]] this time showing his problems with the camp bug collection.
* EarlyInstallmentWeirdness: Mr. Barkin's hair is blond in this episode instead of its usual dark brown.
* ExcuseMeComingThrough: Kim at the beginning of the episode, desperately racing through the halls in a (failed) attempt to make it to class on time.
* {{Foreshadowing}}: Ron appeared to be very interested and was busy listening to Drakken gloating about his scheme while they retrieve the tick disk. Fast forward to [[Recap/KimPossibleS3E4BadBoy Bad Boy]], where Ron's SuperpoweredEvilSide is unleashed.
* HelloNurse: Ron's initial reaction to Shego.
--> '''Wade:''' OK. Look. I took that freeze-frame from the security camera. Her name is Shego. She is wanted in eleven countries.\\
'''Ron:''' Make that ''twelve''. [[WolfWhistle Grrrrr]].
* HoistByHisOwnPetard: Drakken falls prey to his own nano-tick.
* IncrediblyLamePun: Actually [[LampshadeHanging lampshaded.]]
--> '''Vinnie:''' Cheerleader's nose is gonna blow!
--> '''Junior:''' That's weak.
* LateForSchool: The episode opens with Kim desperately racing to print out a report and get to class on time. She doesn't quite make it and gets detention for being late.
* NoodleIncident: How Kim helped Gustavo with the flood in his country; it was apparently just like swim class...minus the piranha.
* ObligatoryJoke: Lampshaded when Dr. Drakken gets his cut short:
-->'''Drakken:''' Enough chit-chat! [[SharkPool My pets are famished!]] Perhaps you two could stay--\\
'''Kim:''' For lunch?\\
'''Drakken:''' ''(defensively)'' I wasn't going to say that!\\
'''Ron:''' Oh, dude, you were ''so'' -- "for lunch".\\
'''Drakken:''' ''(exasperated)'' Aargh! Yes! Then -- stay for lunch! ''(dumps them in)''
* OhCrap: Drakken, after his computer informs him the nano-tick is gonna blow.
* OutOfOrder: This episode is clearly Team Possible's first encounter with Dr. Drakken and Shego, who were seen earlier (by original broadcast order) in [[Recap/KimPossibleS1E1Crush "Crush"]].
* PantyShot: It's in the opening sequence too, so you should know when it happens.
* TheReveal[=/=]CaptainObviousReveal: We first see Drakken by flickering firelight, obscuring his [[AmazingTechnicolorPopulation blue skin color]] to be revealed later... except that it's already been seen in "Crush".
* SharkPool: Drakken has one in his lair, which he, surprisingly has never used again.
* ShoutOut: "Haunted Island? keep out [[ScoobyDoo meddling kids?]] (scoffs) please."
* SpinningClockHands: Parodied -- the clock hands speed up while Kim is in detention until Mr. Barkin [[PercussiveMaintenance hits the clock]], mutters that it's broken again, and resets it to indicate that only five minutes have passed.
* StickyBomb: The nano-tick.
* ThisCannotBe: Drakken is absolutely shocked when Shego is defeated, apparently for the very first time. Of course, he has plenty of opportunity to [[FailureIsTheOnlyOption get used to it]].