The Magical Map is a map used in Paper Mario: The Thousand-Year Door. The Magical Map is the only thing that is able to detect where the Crystal Stars are. The Magical Map is the first important item, or item for that matter, that Mario recieves in Paper Mario: The Thousand-Year Door.
After the Four Heroes got all seven Crystal Stars, they were able to fight the Shadow Queen. After defeating the Shadow Queen, they fused her spirit into a treasure chest. But, the Shadow Queen cursed the Four Heroes as she was destroyed. When the Heroes would let go of the Crystal Star that they held, they would turn into a Black Chest Demon. So, the heroes decided to create the Magical Map. This was done so that a future hero could find the Crystal Stars easier. To make sure no one evil got hold of the Magical Map, they placed the map inside a container. This container could only be opened by one pure of heart, but that doesn't prevent evil people from getting the container.
Beldam somehow got hold of the container and showed it to Sir Grodus. Beldam said that only the pure of heart could open the container. Since only a woman of pure heart could act as a sacrifice for the Shadow Queen, it would be the perfect opportunity to find a sacrifice. Grodus agreed, and gave Beldam the task of finding the woman of pure heart.
In Game Edit
Beldam dressed up as a merchant in Rougeport. When Princess Peach asked if she could buy something, Beldam gave her the container. Peach is pure of heart, and so she managed to open it. There were too many witnesses around, and so Beldam could not kidnap Princess Peach then. Peach managed to send the Magical Map to Mario by mail before getting herself kidnapped. At Mario's Pad, Luigi brings in the mail. He finds the Magical Map, and gives it to Mario. A note attached to the Magical Map tells Mario to go to Rougeport, so Mario and Luigi does so. When Mario meets up with Goombella, Goombella brings Mario to Professor Frankly, who tells Mario about the map's powers.
Professor Frankly brings Mario and Goombella to the Thousand-Year Door, and Mario stands on the pedistal. The floors light up, and the location of the Diamond Star is revealed on the Magical Map. Each time Mario collects a Crystal Star and stands on the pedistal, the next Crystal Star appears on the Magical Map. A few items also appear next to the Crystal Star to tell what kind of an environment. Like with the Emerald Star in the Great Tree, trees appear next to it. For the Diamond Star in Hooktail Castle, a castle appears.