During this season the miniseries Elements aired, which follows Finn, Jake, and BMO after they return home to discover that extreme elemental magic has turned Ooo into a dystopia. The season was storyboarded and written by Adam Muto, Sam Alden, Polly Guo, Seo Kim, Somvilay Xayaphone, Laura Knetzger, Steve Wolfhard, Tom Herpich, Graham Falk, Kent Osborne, Hanna K.
Finn and Jake live in the post-apocalyptic Land of Ooo, where they interact with the other main characters of the show: Princess Bubblegum, The Ice King, Marceline the Vampire Queen, Lumpy Space Princess, BMO, and Flame Princess. The season follows the adventures of Finn (a human boy) and his best friend and adoptive brother, Jake, a dog with magical powers to change shape and size at will. The ninth season of Adventure Time, an American animated television series created by Pendleton Ward, premiered on the Cartoon Network on April 21, 2017.