The Evil M, maltazard, is evolving and 7 feet tall one of the humans, wherever he belongs, causing terror. His goal is simple: forming an army of henchmen that are giant and ruling over the universe. Meanwhile, Arthur is a Minimoy, and thus in a country where he is unable to off him. With the aid of Selenia and Betameche, he hatches a plan to regain his standard size: all they have to do is Arthur's house through the pipeworksand catch an electric train out of his bedroom to his grandfather's study and detect an elixir that may cause him return to his human size. If it weren't for Darkos hot on the tails, sounds simple enough.