Mario and Princess Peach are having a picnic around Peach's Castle, when Bowser Jr. jumps out from behind a bush and steals Peach. Mario chases after him, until he's stopped by the Koopalings, who knock him back into Princess Peach's Castle. Blue and Yellow Toads find him there and wake him up. They tell him that after Bowser Jr. kidnapped Peach, Bowser and the Koopalings attacked the castle. Since Mario was knocked out, Luigi was the only one there to defend the castle. He failed with a lack of help, and the castle was destroyed. Bowser also succeeded in kidnapping Yoshi, and several Toads. So Mario, Luigi, Blue Toad, and Yellow Toad embark on an adventure to save Yoshi, the Toads, and the princess.