The Mushroom Kingdom has been living as usual following the events of the first movie until a new threat suddenly appears in the form of a powerful sorcerer named Magikoopa. He has been using his dark magic to corrupt otherwise peaceful citizens, turning them into horrible monsters.
Mario and Luigi must once again join forces with Princess Toadstool, Yoshi, and the other citizens of the Mushroom Kingdom in order to stop Magikoopa and save everyone from his tyranny. As they venture across the kingdom, they cross paths with old foes like Bowser and even discover a new ally in Wario.
The brothers must use their newfound skills and knowledge to outwit Magikoopa and his arsenal of tricks. In the end, they must battle him in an epic showdown in order to put an end to his reign of terror and bring peace back to the Mushroom Kingdom.