While returning home from their adventure in Islands, Finn, Jake and BMO take a nap after eating a lot of bananas. A mysterious black orb in the sky begins to subject the three to strange dreams that quickly become nightmarish. Their nightmares begin to intertwine as they realize that they are dreaming and come in contact with a being that Finn dubs Nightmare Princess. This entity simply wants their bananas, but BMO strikes a bargain so that they get something in return. The group wake up to the orb taking some of their bananas and leaves a pink vile of nightmare juice. BMO looks through the telescope to discover that Ooo has changed radically.
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.