Chapter 1

Mario and Goombella show the updated map to Professor Frankly, who reveals that the first Crystal Star is in Petal Meadows. To reach this place, they must find a pipe in Rogueport Sewers. After finding it, Mario and Goombella arrive to Petal Meadows, where they see Hooktail and her castle. The duo stops at a nearby village called Petalburg and discover from the mayor that the dragon Hooktail has been terrorizing the village. The mayor tells them that Hooktail guards the Crystal Star in her castle, and that to access it, they must find the two stone keys in Shhwonk Fortress. After finding them, Mario and Goombella march to Hooktail's castle, with Koops in tow (who wants to defeat Hooktail to avenge his dead father and become stronger). After navigating through the castle's traps with the help of Koops, they encounter the dragon and defeat her, allowing Koops's father to get out of the dragon's gut and present Mario with the Diamond Star.

Somewhere else, it is revealed that Princess Peach was abducted by the X-Nauts. When a X-Naut tells Sir Grodus someone got the first Crystal Star, Peach accidentally blurts out Mario's name. Grodus hears this and orders the Shadow Sirens to steal the map in Mario's possession. Peach soon meets TEC-XX, who develops an interest in Peach's concept of love, and asks for her help to understand it. Peach agrees; in exchange, TEC lets her send e-mails to Mario. During another scene transition, at Bowser's Castle, Kammy Koopa tells Bowser about Mario's quest to find the Crystal Stars and Peach's abduction, things that motivate Bowser to hunt for the Crystal Stars and kidnap Peach back. He and Kammy head for Rogueport.

Back in Petalburg, the group receives an e-mail from Peach, who tells them she has been kidnapped. Mario and co. head back to the Thousand-Year Door and reveal the location of the next star.