King Koopa goes into the fast food business and his food is a hit with everyone in Dome City, except for the Princess. But no one knows that Koopa sneaked in a side effect for those who eat his Egg Scoopa Koopa sandwiches, turning them into Chickadactyls. Only Mario and the Princess remain unchanged so it's up to them to stop Koopa.

Mario invents the telephone for the cave people. He soon regrets it, however, when he and Luigi have to keep protecting the cave people, who are spending all their time talking on the phone.

Luigi tells Yoshi about the Mario Brothers and Princess Toadstool's first adventure in Dinosaur Land.