Mario and Cappy travel through several kingdoms. Mario and Cappy confront Bowser in the Nimbus Arena
Using the power of the Multi Moon obtained from Madame Broode, the Odyssey becomes functional once more, and Mario and Cappy use it to chase after Bowser and the Broodals. Soon after, Mario and Cappy find and defeat Madame Broode, the boss of the Broodals, and her Chain Chomp. After defeating one of the Broodals, named Topper, Mario and Cappy use a spark pylon to travel to Fossil Falls of the Cascade Kingdom, where they find the airship, named the Odyssey, which uses Power Moons as energy to travel. Upon reaching the top, they encounter the Broodals, who were hired by Bowser as his wedding planners. While exploring the tower, Mario captures a frog, first learning of this being Cappy's main ability.
Cappy informs Mario that they may be able to find a usable airship in the next kingdom, accessible from the Top Hat Tower. Mario and Cappy decide to team up to stop Bowser's plans and save both Peach and Tiara, and using the piece he collected, Cappy transforms into Mario's cap, allowing Mario to use his abilities. Upon being calmed down, Cappy introduces himself and explains to Mario that Bowser had not only attacked their kingdom, destroying its airship armada, but had also kidnapped Tiara, his sister, to use her as Peach's wedding headdress. Mario wakes up, startling Cappy, who attempts to flee. Cappy begins nudging Mario to awaken him.