Mario and Luigi get invited by Peach to go to a private amusement park, but when they get there, it's all amuck. And after finding a ghost/shadow siren named Vivian, the 2 brothers embark on a quest to find Peach, stop a new ghostly invasion, and try to have a bit of fun with all the free rides. Heck, it might even be the RIDE OF THEIR LIVES!