From the rules:
Join KERMIT THE FROG, FOZZIE BEAR, MISS PIGGY and THE GREAT GONZO on a wild romp through the streets of London. Your favorite Muppet friends are in search of four very hard-to-capture thieves who are trying to steal a legendary jewel called the "Baseball Diamond". Join the Muppets on their adventure. If you're the first player to catch the four thieves and save the "Baseball Diamond", you'll wind the game.
Here's some of the fun you'll have...take a cab and a bus, both of which are controlled by hidden wheels underneath the gameboard...be careful, though...if you spin the wheel too much or too little, you'll miss your bus or fail to hail a cab! Visit the Dubonnet Club with its mysterious spinning room and the Mallory Gallery where the "Baseball Diamond" is hidden. To enter the Gallery, you must make a precarious climb up the side of the Gallery Building. Then before you can save the jewel, you must be sure you own four different Thief cards. If you own the four cards, turn the hidden dial in the Gallery hoping that the jewel will be set free and come rolling out the front door of the Gallery (the jewel will be dislodged only when this hidden dial is spun a certain number of times). The player who frees the jewel from its hiding place wins the game. Have fun!