In the episode, he holds Candy People hostage. His intentions were to steal Princess Bubblegum's crown due to an event in his past. In his youth, Princess Bubblegum visited an orphanage he lived in to cheer all of the depressed children up. When Baby-Snaps told her he wanted to be a princess like her, Bubblegum giggled a bit and patted his head. Cookie saw the gestures as cruel and unkind.
Cookie befriends Jake (who is disguised as a milk man) thinking that he also hates Princess Bubblegum.
Cookie eventually becomes disheartened and agrees that he'll never be a princess. To avoid being sent to jail by the Banana Guards, he attempts to commit suicide by falling off a cliff into the Candy Gorge; however, he survives, although broken in many pieces.At the end of the episode, he winds up being re-assembled in the Candy Kingdom Mental Hospital, where Jake gives him the crown from the Grass Lands making him its unofficial princess.