Masquerade has been destroying kids' Bakugan all over the world and the Brawlers decide to put a stop to it. Runo, Marucho along with Dan take a trip to recruit Shun to join them and make their team even stronger. But when they arrive at Shun's house, Dan finds out Masquerade is already there. Masquerade wants to battle Dan and send his Drago to the Doom Dimension and, without hesitation, Dan accepts his challenge. It's a tough battle, especially since Shun has teamed up with Masquerade. Dan loses the first two battles, and now he's left only with his Drago. Things go from bad to worse as they have Dan pinned down. It looks like the end for Dan and his Bakugan when...Shun switches sides and at the last minute, turns his Bakugan on Masquerade and defeats him! Masquerade is boiling mad and as he leaves, he tells both of them 'This isn't over!' And it's not, because in the end, Shun decides to join Dan in his quest to defeat Masquerade!