Peach's Castle
The Blorbs! Mushroom Kingdom marred by mysterious malady! The Blorbs! It comes without warning! First, you balloon up to blimp size! Then, the rolling! You roll away! Oh, the horror of the blorbs! As of press time, the cause and cure are unknown... Day by day, the number of blorbed Toads swells... Seeing how grave the situation is, Princess Peach convenes an emergency meeting at her castle...
Peach calls on Starlow, a star sprite, to try and cure the blorbs. Unfortunately, the blorbs cannot be cured by even a star sprite. With the doctors stumped, Peach calls for Mario and Luigi.
After an action-icon refresher, you finally take control of Mario and Luigi. Head straight on into the next room where you can hit the ? blocks for coins. In the next room, hit the save block, then go to the right into the conference hall where you get to fight Bowser.