A year after returning from the warring worlds of Gundalia and Neathia, Dan Kuso and his friends are back on Earth, and the virtual arena of Bakugan Interspace has recovered from the alien invasion. Exposure to Code Eve, the Bakugan Mother spirit, has given Dan's partner Drago enormous power, but whenever Drago battles, Interspace suffers disruptions. Dan cannot control these new abilities, and he accidentally releases Mechtogan, a mysterious mechanical being that attacks friend and foe alike. Meanwhile an unknown mastermind sends mutated Chaos Bakugan into Interspace to brainwash brawlers and seize the virtual world. Dan must rein in the Mechtogan and rally the Battle Brawlers once more in this action-packed mecha adventure.