A being of incredible power, known as a codemaster, arrives in Mainframe, demanding they bring out another codemaster who he believes is hiding there.

Megabyte is draining energy from the games to fuel his attempt to breach the Mainframe archive's protective barrier. But when he takes too much, the game crashes and merges with a new one, trapping him and Bob inside the chaos.

Megabyte makes a grab for the core energy, but ends up getting trapped with it inside a corrupt game. Now Bob must keep the game going until he can get the energy back to the Principal Office or Mainframe will shut down when game ends.

Mainframe is thrown into utter chaos when Hexadecimal manages to tap into the system's paint function.

Enzo is feeling along since there are no sprites his age in Mainframe. Dot won't let him enter games with Bob and Frisket comes and goes has he pleases. So when a game cube drops on the Diner and he runs to a young female sprite named AndrAIa, he's all too quick to make friends with her. But there's something Enzo doesn't seem to realise about AndrAIa...

Mike accidently shatters Hexadecimal's looking glass, unleashing a horrible black parasite that infects the virus. Suddenly, all the nulls react, flocking to Lost Angles, covering the altered Hexadecimal until she's became a gigantic mass of nulls, walking around and flattening random buildings.

The infected Megabyte merges with Hexadecimal, turning into the energy devouring super-virus Gigabyte. It must be stopped before it gathers enough power to create a portal to the Net.

Two special agents from the CGI are investigating disappearances in level 31. Their prime suspect is Mouse but the real abductor ends up being something far more dangerous: a web creature. The Guardians would destroy all of Mainframe to kill the web creature, but Bob has other ideas.

Above Mainframe hangs the web creature's parting gift: A gigantic portal to the Web - a chaotic abyss filled with unspeakable horrors. It will take the combined might of all inhabitants of the system to close it, including the viruses, but can they be trusted?