Wonderland
Wonderland is one of the first worlds you'll reach by the Gummi Ship. Upon entering, you'll noice a White Rabbit hopping around. Head towards the door(s) and you'll find yourself in a small room with a tiny Doorknob. After speaking to him, drink the bottle on the table that just poped out, but push the bed out of the way first. After shrinking, head to the tiny passage that was behind the bed, and a cutscene will begin.
A girl named Alice has been captured, and you'r main object is to find four pieces of evidence to proove she is innocent. While it's possibe to collect only one to continue on, it's better that all four be collected. Some are found around the Lotus Forest; the others in the Bizzare Room, with their locations only accesable through hidden entryways around the forest.
You'll soon have to present the evidence to the Queen of Hearts, who will also add in her own. Who the culprit is depends on the box you chose. You have to pick one of five, which have all been mixed up to make things tricky. Chances are; if you did not collect all four, there is a chance that the "culprit" may be Donald, Goofy, or both; if all four are collected, the culprit might be a Heartless. Alice's cage will be lifted so that you cannot rescue her. You must attack the Crank Tower, while the cards will attack you. You can stun them by attacking the Queen; once she is knocked over, some cards will be stunned.
After the battle, it's revealed that Alice had vanished. The same cat from eariler will explain that some "shadows" have kidnapped her, and that there is a dark room. If you torch the lights in the Bizzare Room (which now has a gravity change) you'll be able to stop the shadows.