Princess Peach finds a map in an old town filled with crime. Mario sets off to the town of Rogueport, where he finds the Crystal Stars (powerful star shaped stones; when all seven are collected the Thousand Year Door opens). There is a door deep in the sewers of Rogueport (the Thousand-Year Door) which will open if all crystal stars are collected. It is said that a demonic spirit rests behind the door. The X-Nauts (a group of robot-like people that are trying to collect the crystal stars in order to awaken a demon to destroy the world) try to steal all crystal stars in order to awaken the evil demon and wipe out the planet so that they can become dictators of the world.