Finn, Lumpy Space Princess, and Gunter arrive in a radically altered Fire Kingdom. The inhabitants, which include Wyatt (voiced by Andrew Daly) and Lady Rainicorn, attack the heroes. Finn and Gunter try desperately to restrain their violent tendencies as it would allow the kingdom to corrupt them. Eventually the group find Flame Princess who has transformed into a dragon. When she swallows the jewel necessary to save Ooo, Finn gives into his violence and begins attacking Flame Princess. Lumpy Space Princess angered by the violence yells at everyone to stop their fighting. The kingdom misinterprets her anger and decide to start a war with the Candy Kingdom. Cinnamon Bun, who was unaffected by the corruption, frets that this is the end of Ooo.
Adventure Time, originally titled Adventure Time with Finn and Jake, follows two best friends: Finn (a 12-year old boy) and Jake (a wise 28-year-old dog with magical powers), and the surreal adventures undertaken by the duo as they traverse the mystical Land of Ooo. A world built for adventure, Ooo is filled to the brim with various landscapes for the two buddies to explore and bizarre characters to assist.