Mario, Luigi, Donkey Kong, and Toad are with Rosalina transporting mysterious new power-ups that could cause serious damage if they fall into the wrong hands from the Planet Daggler to the Mushroom Kingdom when a large spaceship piloted by Waluigi attacks their spaceship and shoots a missile at it, sending it flying out of control. It crash lands on a mysterious planet that has been taken over by Wario and dubbed Wario World. Rosalina discovers that the power-ups have been spread throughout the planet. Mario and his pals set out to find all the power-ups and defeat the Wario Bros. before it's too late!