Having vowed revenge on her for all the injustices placed upon them, Dr. Wakeman's mutant lab rats, led by the evil genius Vladimir, also known as Mr. Scruffles, plan to destroy her by taking control of Jenny's body.

Jenny wants to go to the town fair, but Dr. Wakeman fears that Jenny will spook the townspeople with her presence. When Jenny gets a hold of a prototype "exo-skin" for her to wear, she sees her chance to mingle with the fairgoers; unfortunately, its mangled appearance only scares them. Meanwhile, Tuck attempts to conquer his fear of Ferris wheels.

On her first day of high school, Jenny seeks to make some new friends, and she thinks she can find some in the arrogant Brit and Tiff Crust. Unfortunately, the Crust cousins do not share the same feelings and plan to humiliate her.

When Jenny saves local school geek Sheldon from a gang of bullies, he quickly becomes smitten with her and does not want to leave her alone.

A simple snowball battle between Jenny, Brad, and Tuck is interrupted by a strange robot ambassador who wants to make Jenny the newest member of the Cluster, a legion of robots headquartered on the planet Cluster Prime that plans to enslave humans for manual labor. When she refuses, the ambassador commences war against her.

Jenny wants to get ear piercings, but her mother refuses to give her ears. Sheldon offers to step in and help, but the ears he builds end up being disproportionately large on Jenny's head.

Brad is disappointed by his lack of a driver's license, and Jenny's attempts to help him. Soon, he takes up joyriding in abandoned UFOs as a new hobby.

Jenny and Brad's secret party is a hit, but between keeping the party-goers under control, keeping the house in one piece, and keeping a group of tiny multiplying aliens from invading Earth, Jenny has her hands full.

While on a mission in Japan, Jenny winds up losing one of her language system discs for English speech. Unable to switch off from speaking in full Japanese, she encounters problems in speaking to people. She uses this to her advantage, however, to make peace with a Japanese creature that grows with and is hurt by water.

Dr. Wakeman is proud of her newest enhancement for Jenny: multi-functional eyes that can see anything in any view. Jenny likes them until she sees how they look on her. She refuses to use them and fumbles around town without any sight until she finally realizes she needs them to fight an invisible villain.

Jenny has been invited to her handsome classmate Don Prima's latest party, and she has gotten a tune-up and a new paint job just for the occasion. However, Brit and Tiff are ready to do anything to sabotage Jenny's chances to impress at the party.

The owner of Mezmer's, a popular hangout spot for teens all over town, enforces a strict "No Robots" policy. Desperate to get in, Jenny dons the new and improved exo-skin to pass off as a glamorous human teenage girl. However, the exo-skin turns out to have a mind of its own and refuses to let Jenny take it off or fight a group of alien space bikers.

Tuck keeps interrupting Jenny's daily activity for every possible favor. When a big problem arises, however, Tuck's call for help winds up going ignored.

When Jenny finds and reactivates her "sisters"–early XJ prototypes 1 through 8–she is beyond happy. Each sister has her own personality, however, and they do not all have the same level of friendliness that Jenny has.

Having been found to have only been activated for five years, the school system declares that Jenny has to be moved into a grade level that corresponds to her "age." Jenny finds herself being forced to adapt to kindergarten.

When Jenny starts to develop face-bolts, voice changes, and excess wires growing out of her body, Brad chalks it up to puberty. However, it soon becomes apparent that the "puberty" is actually the doing of Queen Vexus of the Cluster, who has infected Jenny with a virus to warp her into a loyal, Cluster-controlled monster.

Jenny becomes the star football player of the high school football team. At a championship game, she soon finds herself facing the former Tremorton High quarterback whom she replaced.

Thanks to a screw-up from one of his Cluster troops, Commander Smytus loses a cache of super-powered Pip Crystals to the Crust Cousins. The cousins decide to flaunt both their style and newfound powers in front of Jenny, and she must use her keen fashion sense to save herself in time.

Looking to prove to Jenny that boy robots are jerks compared to him, Sheldon creates a mechanical suit and dubs himself the "Silver Shell". The plan backfires, however, when Jenny starts falling for Silver Shell.

As a robot, Jenny wants to experience what it is like to dream. When Dr. Wakeman installs a dream chip, Jenny's joy causes her to abuse its function and she finds herself stuck in dream mode and sleepwalking, causing mayhem in the process.

Jenny's desire to know the feeling of physical contact leads her to steal a set of artificial nerves from Dr. Wakeman. The nerves, however, have only two settings: tickle and pain. Jenny must manage these while fighting Himcules, a villain whose strength increases when he sees others in pain and diminishes at the sound of laughter.

Sheldon sets Jenny up for a date with Silver Shell, in hopes that he can reveal himself to her. However, she already has a date with Don Prima, much to Sheldon's chagrin. An evil mutant fly that can eat metal attacks people in the restaurant while the date takes place, while Silver Shell tries to sabotage the date by ruining Don's beautiful shoes.

Jenny is stuck going to a robot convention with Dr. Wakeman. Snubbed by all the other robots and insulted by Dr. Wakeman's rival, Dr. Phineas Mogg, Jenny finds herself going to a robot called Vee for comfort. However, "Vee" is actually Vexus in disguise, seeking to recruit new Cluster members.

Jenny gets a chance to visit the theme park Wizzly World with Brad and Tuck, and she cannot help but think that the robots in the park feel miserable. When Jenny breaks them out of the park, however, chaos ensues.

When Jenny hangs up on Dr. Wakeman one too many times, the doctor desperately reprograms Jenny's communicator to make Jenny unable to turn it off.