Mandark gets inside Dexter’s computer system and creates a computer virus, so Dexter must follow him inside and kick him out from cyberspace. However, Dee Dee has other plans in mind.

Dexter’s father tries to watch a golf tournament, but is constantly interrupted by his wife, Dexter, and Dee Dee.

Dee Dee’s stuffed animals come to life and roam the house when Dee Dee uses a formula that brings inanimate objects to life, which delights Dee Dee, much to his dismay.

When Dee Dee eats a contaminated apple, she turns into a monster every time when she tells Dexter what to do.

Old Dexter And Old Dee Dee’s talks about the glory days, and his sister is still there to inject her opinions, telling him what really happened.

While out for dinner at a pizza restaurant, Dexter tries to slow down the “Whack the Weasel” machine to win a stuffed Monkey doll before Dee Dee does. Security captures him for tampering with the machine, and he falls into the hands of a mad scientist.

Dexter creates a robot to assist him, but the robot starts controlling his lab and tries to destroy Dexter.

Dexter’s new device allows him to study for the next day’s French test while sleeping. It malfunctions, causing a single phrase (omelette du fromage) to repeat throughout the night, causing Dexter to wake up the next morning speaking nothing else except omelette du fromage.

Dexter’s lab is threatened with repossession unless he can repay his debt to NASA. When Dee Dee wins the same amount in a lottery, he decides to steal her money out of desperation.

When Dexter’s computer gets laryngitis, Dexter must find a replacement voice.

Dexter is forced to take Dee Dee to the zoo. There, she ends up trying to save an ostrich with disastrous results. Dee Dee and the ostrich switches their places.

Dexter creates a magnetic field to keep Dee Dee away from him, but it malfunctions, causing them to stick together.

Unable to ride in a roller coaster due to his height, Dexter creates a device to make himself taller.

During a trip to Japan as part of a student exchange program, Dexter accidentally releases a giant monster with an axe-like head from a volcano, forcing him to enlist the aid of his family to defeat it.

Dee Dee inflates Dexter’s hydro-plasmatic suit and constantly floats in the air, prompting Dexter to bring her down.

Dexter refuses to admit that blondes have more fun, so Dee Dee secretly dyes his hair blond to prove it to him.

Dee Dee accidentally shuts down Dexter’s lab, and he has to power it back. In the process, Dee Dee attempts to keep Dexter from finding out what she really did.

Despite warnings from the computer, Dexter consumes too much power while performing numerous experiments, causing his lab to shut down.

When Dexter uses anti-matter on the family car to shorten road trips, he accidentally fuses Dee Dee with the car.

To keep himself from forgetting anything important, Dexter uses a device to copy his memories, which causes a mayhem in his own head.

When Dee Dee causes Dexter to mistakenly take a book from the library without checking it out, they sneak into the library at night to put it back.

Dad decides to give the car a retouch, but keeps breaking things and saying he will fix it later. After having enough, he pushes the car over a cliff, and below it are other crushed cars, meaning this was not the first time.

When Dexter is asked to bring his mother to school, he disguises Dee Dee as her so that she can take her place, but Dee Dee does not behave like their mother.

Dee Dee dares Dexter into building her a giant robot similar to his Robo-Dexo 2000. They then team up to try to save an island’s population from being destroyed by an erupting volcano using their giant robots.