The episode opens with Odd locking himself in his and Ulrich's dorm room to sulk. When the other Lyoko Warriors convince him to open the door, it is revealed that another of Odd's short films will be featured at Kadic Academy's Short Film Night and that Odd's parents are visiting the school specifically to watch the film. However, because his parents are incredibly loving and supportive, Odd finds them embarrassing and does not want them to come. Meanwhile, Sissi arrives in her father's office to tell him that her cell phone has stopped working. When he is unable to fix the phone and accidentally puts a screwdriver through it and breaks it, Sissi, upset, storms out of the office.
That afternoon, a small crowd gathers in a classroom-turned-makeshift theatre, and Mr. Chardin introduces Odd's film, titled Mandibles and Purple Mauve. Jeremie brings his laptop with him to the screening, but turns it off, not wanting the superscan to interrupt the film. However, before the film starts, Odd is discovered to be missing from the audience and Ulrich is forced to find him and convince him to come to the screening. As Odd gives a feeble speech regarding the film, it is revealed that X.A.N.A. has activated a tower in the Mountain Sector and sent a spectre into the antenna connected to the Science Building.
Just before Odd begins the screening of the film, the cell phone of his father begins ringing. When he goes outside to answer it, the possessed antenna sends a signal to his phone that hypnotizes him immediately. When he returns he gives the cellphone to his wife and she also becomes hypnotized. Then the all cellphones of everyone in the auditorium suddenly start ringing, which causes more and more people to fall under X.A.N.A.'s spell. As the brainwashed audience begins exhibiting hyper-aggressive behavior, Jeremie becomes suspicious and turns his laptop back on, discovering the activated Tower. Jeremie, Ulrich, Yumi, and Aelita then slip out of the theatre and begin traveling to the Factory. However, when Odd attempts to follow them, the crowd becomes a mob and begins advancing on him, forcing him to flee.
The others arrive at the Factory as Odd takes refuge in the empty cafeteria. Deciding that the best way to help Odd is to deactivate the tower as quickly as possible, Jeremie sends Aelita, Yumi, and Ulrich to Lyoko. The tower is on top of huge platform and the heroes landed on the pathway beneath it. It is then revealed that X.A.N.A. has implanted a virus in the Supercomputer that makes it difficult for Jeremie to execute commands on the lab interface, and he only manages to virtualize one vehicle, the Overwing, to the trio. Yumi and Ulrich board the Overwing while Aelita triggers her angel wings, and together they fly towards the tower, which is located on top of a summit. However, they are soon ambushed by a swarm of Mantas and the Overwing is destroyed, causing Ulrich and Yumi to fall. As Aelita battles the monsters, Yumi and Ulrich catch themselves on the face of a mountain thanks to the latter's katana, leaving them both dangling over the Digital Sea.
Meanwhile, in the cafeteria, Odd is attacked by Nicholas and Herb, but is saved by Sissi, who, without a cell phone, has not been brainwashed. The rest of the mob then arrives at the cafeteria and chases Odd and Sissi into the park. On Lyoko, Aelita defeats the Mantas while Jeremie continues to have trouble with X.A.N.A.'s virus. Ulrich eventually loses his grip, causing him and Yumi to plummet toward the Digital Sea. Fortunately, Aelita uses her Creativity to conjure a small platform, which breaks their fall.
Odd and Sissi attempt to hide in the garden shed, but are attacked by Mr. Riley, the groundskeeper. After running away from Riley, Sissi and Odd are finally cornered by the mob. Meanwhile, Yumi, Ulrich, and Aelita are attacked by Krabs from on top of the mountain. Yumi dives off the platform Aelita created in order to defeat one of the monsters, and lands on a path far below. However, she is then devirtualized when a Kankrelat appears behind her. Ulrich and Aelita remain pinned between the Kankrelat and the remaining Krab until Jeremie manages to send Ulrich the Overboard. As Ulrich and Aelita travel up to the activated tower together, Aelita is shot down by the Krab and lands by the tower. Fortunately, Ulrich manages to defeat the Krab before being devirtualized, allowing Aelita to enter the tower.
The mob takes Odd and Sissi up to the roof of the Science Building and demands they both jump to their deaths. However, when they attempt to stall, Mr. Delmas and Mrs. Della Robbia move in to push them off. Just before Odd and Sissi fall, Aelita deactivates the tower, ending the hypnosis and bringing the people in the mob back to normal. As the crowd comes to their senses, Jeremie activates a return to the past, erasing their memories.
The return trip takes the Lyoko Warriors back to Odd's screening. Grateful for his parents' support and no longer embarrassed by them, Odd energetically narrates his film, which is revealed to be a mock animal documentary using embarrassing footage of students and faculty as the subjects. However, when the film reaches a segment featuring Sissi waking up in the morning, Sissi herself worries about Odd embarrassing her. However, grateful for her help during the X.A.N.A. attack, Odd narrates her kindly, comparing her to a beautiful butterfly hatching from a cocoon. Despite the kindness, Sissi is still embarrassed when Odd winks at her from the lectern.
- The original French name for this episode is Mauvaises ondes, which translates to Bad Vibes in English.
- This is the fourth and last episode in season four in which William does not make an appearance; the previous three being Maiden Voyage, Cousins Once Removed, and Wrong Exposure.
- The Official YouTube Channel has the episode title misspelled. Instead of "Bad Connection", it says "Bad Connextion".
- X.A.N.A.'s attack method in this episode is quite similar to the events of Cell, a novel written by Stephen King.
- X.A.N.A. possesses more people in this episode than any other, with almost everyone in the entire school under his control at the same time.
- Ulrich pilots the Overboard for the first time in this episode.
- Despite Mrs. Della Robbia's voice being heard through the phone when Mr. Delmas called her in A Great Day, this episode marks the only physical appearance of Mr. and Mrs. Della Robbia.
- When Jeremie is warning others not to answer their cellphones, Yumi has blonde eyebrows.
|Code Lyoko: Season 4|
|William Returns | Double Take | Opening Act | Wreck Room | Skidbladnir | Maiden Voyage | Crash Course | Replika | I'd Rather Not Talk About It | Hot Shower | The Lake | Lost At Sea | Lab Rat | Bragging Rights | Dog Day Afternoon | A Lack of Goodwill | Distant Memory | Hard Luck | Guided Missile | Kadic Bombshell | Canine Conundrum | A Space Oddity | Cousins Once Removed | Music To Soothe the Savage Beast | Wrong Exposure | Bad Connection | Cold Sweat | Down to Earth | Fight to the Finish | Echoes|
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