The Bakugan, Drago, who will soon become Dan's closest ally, begins to explain the origin of Bakugan and the Dimension of Vestroia.
It seems a very gifted and mysterious Bakugan player named Masquerade has been stealing Bakugans from kids all around the world.
Masquerade gives the Doom card to a mysterious fighter, Dan faces a brawler named Rikimaru and Runo finds another talking Bakugan.
Dan is having a hard time without Drago around. Feeling frustrated, he takes his anger out on a school friend name Ryo.
Dan and Runo meet for the first time other than on the Bakugan web-site and are surprised that they actually live in the same town!
While at an amusement park, Dan and Runo are invited on stage to assist two brothers performing a magic act.
Marucho reveals that he has secretly moved into Dan's neighbourhood and throws an elaborate welcoming bash.
Dan and Marucho are pitted against the two pop star princesses, 'Jenny and Jewls', who have been recruited by Masquerade.
Masquerade convinces two boys into using the Doom card against the Bakugan Battle Brawlers.
Julie and her childhood friend Billy go toe-to-toe in a Bakugan Battle.
Marucho and Runo realize that the combined strength of the Battle Brawlers doesn't match up to Masquerade's power.
Dan tells Drago about his history with Shun, and how Shun's grandfather wanted him to stop playing Bakugan and focus on becoming a true ninja warrior.
Masquerade has been destroying kids' Bakugans all over the world and the Brawlers need to put a stop to it.
Lured by an invitation to celebrate their world class rankings, five of the top ten Bakugan players gather at a mysterious mansion.
The Brawlers head off to Bakugan Valley looking for the 'Infinity Core'.
While the Bakugan Battle Brawlers continue their search for the Infinity Core; Shun becomes convinced that someone is spying on them.
While searching for information on the infinity core, the brawlers are told to head to Germany, where they're tricked into a deadly battle with Klaus.
Runo and Marucho discover a control room in Klause Von Herzon's castle with a display of rankings of all the Bakugan players from around the world!
Julie finds herself in a brawl with her childhood friend Billy in order to save him from Masquerade.
Dan and Shun have a falling out and Shun takes off on his own to seek out and destroy Masquerade.
The Brawlers are ambushed by Masquerade's gang. A battle ensues, and to the shock of Marucho, his Bakugan Preyas is under the control of the bad guys.
Dan, Marucho and Runo enter into battle with Klaus, Chan and Julio, to try to find out where Masquerade is hiding.
The Brawlers have reason to suspect the webmaster by the name of Joe is spying on them.
Alice befriends a young Bakugan player named Christopher. He loves his Bakugan but is always losing and is on the verge of throwing his Bakugan away.
Runo suspects Alice is secretly spying on the Brawlers and giving information to Masquerade.
Masquerade turns on his own gang and battles them, sending all of their Bakugan to the Doom Dimension!