Answering an invitation, Mario, Luigi and Wario set out for a royal party with Princess Peach. When they arrive at the castle, though, they find it strangely empty. Meanwhile, Yoshi awakes from a rooftop nap to find the castle eerily silent, with Mario, Luigi and Wario nowhere to be seen. Yoshi soon discovers that Bowser has pilfered the castle's Power Stars and imprisoned the Toads in the castle's immense collection of paintings. It's up to the dynamic dino to figure out what happened to Mario, Luigi and Wario and save the day.