The game is set in the Mushroom Kingdom, beginning as Mario and Luigi are relaxing in their house when the mail arrives with a letter, which turns out to be an invitation from Peach to a party. Mario and Luigi then head to the castle, and as Mario is about to have some quiet time with Peach, her castle is suddenly lifted by Bowser's fortress. After his invasion and victory over Mario, the attached fortress serves as the location for playable side quests of the kidnapped Peach. In the main quest, Mario tries to retrieve all of the 7 imprisoned Star Spirits on land, where most of the locations are linked to the central Toad Town, which acts as the game's hub area. The story's main conflict arises when Bowser invades Star Haven, the residence for the Star Spirits, and steals the Star Rod.