Johnny is upset because the holidays that give free candy to the world are spread too far apart, so Johnny decides to start his own holiday, known as Kids Get Free Candy Day, and try to spread free candy. When there are some adult protests against this holiday, Johnny, Dukey, Susan, and Mary gain an unlikely ally against this – the Beekeeper.
Chameleon Boy infiltrates Imperiex's ranks as Persuader. But something goes horribly wrong.
Batman and Robin team up with the Flash to thwart Mirror Master's plans to trap everyone in their own mirror image.
When an embarrassing picture of Yumi is printed in the Kadic newspaper, she turns to Odd as the source. He manages to get Ulrich to take the blame, however, causing tension between him and Yumi. Putting that aside, Jeremie sets up a mission to the next Replika, a copy of the Ice Sector. Its supercomputer is located in Siberia, where XANA is growing brains for an unknown purpose. Odd and Yumi are sent to the real world to destroy it, only to be confronted by William. When trying to shut down the tower, Aelita realizes that the data it is generating could be used to free William. After downloading the necessary data and disabling William, everything seems to be set for destroying the Replika. However, XANA draws on the power of his many Replikas to create a new monster: the "Kolossus," a massive creature resembling a fire elemental with a sword for a hand. It easily devirtualizes Aelita and Ulrich, and nearly destroys the Skid, as well. With this new development, and the realization that XANA has hundreds of supercomputers at his command, Jeremie has to change strategies. Meanwhile, Yumi forgives Ulrich for the picture, and Odd admits to his deception soon after. Yumi gets back at both of them by getting a picture of the two coming out of the shower in the paper.
Odd is presenting one of his films, but is unhappy because his parents are coming. According to him, they never find fault in anything he does, which he finds dissatisfying because he isn't treated like a normal teen. However, when he's finally pressured into it, XANA attacks, using the school's cell phone antenna to spread a virus to everyone who answers their phone to cause them to become vicious, angry mind controlled slaves , starting with Odd's parents. With the widespread use of cell phones, all but the Lyoko warriors and Sissi are affected, Sissi having had her phone accidentally broken by her father. While she and Odd attempt to evade the possessed students and faculty, the others deactivate the tower in the Mountain Sector. Once a return trip wipes everyone's memories, Odd plays his video, which showcases all the humorous moments at Kadic, with Sissi in particular being treated in a positive light as thanks for her earlier assistance, much to her confusion.
In order to defeat XANA, whom they have vastly underestimated, Jeremie plans to design another multi-agent system to combat him. That, however, is still under development. In more immediate matters, Jeremie has figured out how to free William from XANA, but needs to run his program directly from the Ice Replika supercomputer. Meanwhile, William's parents arrive to visit their son, and the strange behavior of his clone concerns them greatly. Back at the Replika, William and two Mantas come to try to sever the translation. However, the Mantas are quickly destroyed by Yumi and Ulrich. William then jumps into the digital void and comes back up with the Kolossus. Jeremie uses some new tricks to stop the Kolossus, allowing Aelita and Odd to reach the supercomputer without worry. However, an army of robotic drones now stationed at the facility complicates matters and they de-translated Odd. With much effort, Aelita is able to run the program to free William before she is de-translated also, but their victory comes at a cost: though William is saved, the Skid is destroyed by the Kolossus with Aelita in it. Fournately, she is devirtualized before the Skidbladnir was totally destroyed. Back on Earth, William is able to take his clone's place, pacifying his concerned parents. Ulrich, meanwhile, has to deal with William's affection for Yumi once more.
When Tom, Peyton, and Kaz sneak into Castle Mommark to scan some of the geneticist's latest experiments, Peyton accidentally releases the cute little starfish creature Stelgar into the wilds of Perim. Out in the sunlight, Stelgar turns into a giant, rampaging monster. Can Peyton find some way to safely stop Stelgar before Mommark's followers destroy him?
A horrified Robin realises that his plan to capture the Sheriff's spy, Henry of Lewes, has failed because he has a traitor in his gang. Fearing for Marian's safety in the castle, Robin sets about rooting out the turncoat. His only clue is supplied by Marian: the spy's meeting place is located at the Trip To Jerusalem Inn, where the traitor outlaw sells his secrets to Gisborne.
Danny and Mike see a strip-club owner get physical with a stripper; Delinda advocates for better rights for exotic dancers in the city; Piper enlists Sam's help to find a racy video that she does not want people to see.
Coreen asks Vicki to check out a string of murders at a goth club. The victims looked like they had been killed by bugs.
When Katara expresses her disapproval of Toph's new way to make quick cash, the group finds her too motherly and tension grows between Katara and Toph. When Katara finally decides to participate in this scam to disprove Toph's accusations, they are left vulnerable and are forced to face the dire consequences.
In an episode told only through music and singing, Skull Boy decides he needs to find out who he is once and for all.
Cleo is worried when she sees her dad around with another woman. When she arrives at their house, she turns out to be Charlotte's mother! Meanwhile, Rikki and Emma attempt to save the Sertori's dinner with their powers.
Melinda and Professor Payne meet with another college professor who discloses that she had an affair with a student. That student just passed away after an accident.
When Dean Loward finally closes a problem fraternity house, the university uses it for overflow housing, placing four freshmen under the supervision of the former fraternity president and his sometime girl friend.
After Harper is hired at the sub station, Alex uses magic to help Harper overcome her clumsiness, which eventually backfires on Alex. A whiz kid is upset for losing business when Justin starts a tutorial service.
Coach Taylor returns to Dillon, but it is not an easy homecoming; the team must deal with conflict between Saracen and Smash; Riggins turns to Lyla for help in changing Street's mind about surgery.
Don feels responsible for a life lost. The victim was in the Witness Protection Program, but she wasn't the only one keeping secrets...what is Don hiding?