Big Bug
Air Date (US) April 23rd, 2004
Air Date (France) October 1st, 2003
Written by Alain Serluppus
Storyboard by Luis Ruiz
Season 1
Episode # 5
Production # 105
Preceeded by Log Book
Followed by Cruel Dilemma
Big Bug is the fifth episode of Season 1 on Code Lyoko.


X.A.N.A. has created a computer virus and sent it out on the internet. All the city’s data-bases have been damaged. Although the problems this causes are quickly solved without major incident, the railway control center has been hit very hard and can no longer stop two of its trains which are on a collision course. One having deadly chemicals as cargo.

Our heroes are faced with an urgent situation. They must counter X.A.N.A.’s evil plan and stop this deadly collision from occurring. And to think that Sissi is going to go after Ulrich again and make our dream team’s mission even more difficult!

As per usual, Aelita deactivates the tower, with the trains being only a few meters from colliding.


  • The original French name for this episode is Big Bogue.
  • This marks the first appearance of the Blok.
  • It was the first episode where Christine Flowers was replaced by Jodi Forrest. It was also when Christophe Callabero was replaced by Matthew Geczy.
  • The train with the toxic chemicals was train #3611.
  • The other train was train #9432.


  • In the study hall, Sissi's legs are shown instead of Odd's.

External LinksEdit

The original episode summary can be found here.



Quality: 480

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ca:Un gran amor es:Un virus muy gordo fr:Big bogue pl:Odcinek 5 "Wielki wirus" pt:O poderoso vírus ru:Важная шишка