When a pen pal of Jimmy's brings herself and her siblings to his dimenion seeking Jimmy's help, he is dragged into a multi-dimensional war with a magical entity. Worse still, his own villains get involved in the conflict. Meanwhile, Royal Woods most famous family, the Louds, have mysteriously vanished. How will their family and friends react?

Lisa Loud builds a portal gun that can transport anyone to any universe imaginable, she takes Lincoln with her to Retroville to meet Jimmy Neutron and they enter the universe with a very 3 dimensional feel. There is also evil brewing with Beautiful Gorgeous and Professor Calamitous with them trying to take over other worlds.