A policeman white blood cell, with the help of a cold pill, must stop a deadly virus from destroying the human they live in, Frank.
By way of a simple mosquito bite, Ozzy and Drix are transferred into the body of a 13-year-old boy, Hector. Unfortunately, a nasty germ named Scarlet Fever is also transferred, and our heroes have to capture him before he wreaks havoc on the City of Hector.
Ozzy accidentally produces a neural spasm that causes Hector to kick the school bully. When the bully threatens to beat up Hector after school, Ozzy has to figure out a way to help Hector defend himself.
Ozzy becomes jealous of a super agent (Penicillin G) who has been injected into Hector to track down a powerful germ known as Strepfinger.
When Ozzy discovers there are lice eggs in Hector's hair, he and Drix venture onto the scalp to knock the eggs off, only to end up running into the monstrous Mother Louse!
Drix's new pet dog, Dander, is mistaken for a Allergen that is threatening the city.
Drix tries to learn how to act ""street"" and ends up helping an acne germ create a huge zit on Hector's face.
Ozzy, Drix and Maria commandeer a submersible police craft into the intestines to stop a gas build-up that threatens Hector's social situation.
Ozzy must keep Nick O'Teen from getting to the brain where he will cause Hector to smoke.
When Sal Monella, a poisonous gangster germ, kidnaps the Mayor with plans to poison Hector, Ozzy and Drix must come to his rescue.
Ozzy thinks he's going to have a baby, but it turns out he's been infected with an intracellular bacteria by returning villain Strepfinger. Ozzy and Drix must find a way to destroy the parasite growing within Ozzy before it spreads its infection to all of Hector.
The Mayoral election is coming up, and Spryman's opponent, a nerdy brain cell named Sylvian Fisher, is using a secret growth formula to cause destructive growth spurts and make the Mayor look bad. Ozzy and Drix must stop this fiendish plan, which becomes more difficult when Sylvian takes the growth formula himself and becomes a raging, muscular monster.
Hector binges on candy, creating a sugar rush that speeds up all the cells and causes the bacteria population to swell. When his parents cut him off sugar, his drop in blood sugar slows all the cells to a crawl. But the bacteria need sugar, so they form an army to raid Hector's sugar reserves. Now Ozzy and Drix, with the help of the Mole, must take on the bacterial army.
Hector's terrible recurring nightmare is keeping everyone in the City of Hector awake. Ozzy and Drix go to the ""Subconscious Network,"" where dreams are produced, and enter Hector's nightmare to help him face his fear.
Ozzy gets transfered into a girl named Christine's body when she gives Hector mouth-to-mouth when he jumps off the high dive to impress her, while there Ozzy starts changing colors and acting like a girl also he is arrested because they think he is a virus.
Ozzy is still in Christine, using REM sleep (or Random Eye Movement). He calls Drix for help, thats when he learns he's gender morphing. When a cell from a certain gender goes to a body of another gender, that cell becomes that gender. With Drix's plan, and the help of another Drixinol cold pill in Christine called ""Drixina."" Ozzy might come back to Hector, and keep Christine from having pneumonia.
Everyone inside Hector forgets who Ozzy and Drix are when Hector experiences a concussion, forcing them to locate the site of the concussion, so they can reboot Hector's memories.
Hector eats a sausage that he barely cooked and gets sick which leads him to getting two worms in his the male worm dies after mating, but the female survives, so Ozzy tries to kill it along with a crazy captain and Drix.
Hector discovers hair growing on his chin; testosterone gang ties up the mayor and wreaks havoc.
After getting injured on a police case, Maria is sent home to rest for the week. She decided to use this time to work on a family reunion coming up for her. Drix notices a rip on the corner of Maria's family picture. Maria doesn't seem to want to talk about it but then Ricky comes in and starts putting the puzzle pieces together. Maria and Ricky share their past with Drix which turns out as Ricky being the family prankster. Maria lost his trust in him so Drix decides to help Ricky get it back. He allows him to be a private eye along with Ozzy with not so good results.
Hector uses a Nose spray to clear his nose, and Drix's Aunt appears. Suddenly, there's a drop in water in Hector and Ozzy thinks Drix's aunt is causing it.
Hector is super-sizing at fast-food resturaunts far too much, which gives Sticity, a bad cholestrial beatnik, the chance to kidnap a fat cell family's child, in an atempt to clog an artery. Can Ozzy and Drix (and the new navigational system, installed by Drix, named Backseat) return the huge blob to his parents in time?
While snowboarding with Travis, Hector crosses an off limits area. Hector starts to freeride, but falls and makes a rip in his trousers. This causes a virus named Cryle to drop Hector's temperature. Ozzy and Drix get ready for a day at the beach, but have to stop Cryle from making Hecotr die of hypothermia.
When Hector accidently breathes in lead, the lead gang cause him to make him feel ill. The Mayor then makes Hector eat cereal so he can bring in The Supplements.
Ozzy goes into mitosis and a four armed evil clone doubles from him trying to steal the iodine.
Hector's appendix is about to burst.
Hector eats too much sugar and doesn't brush so he gets a cavity caused by General Malay.
