Little Nemo is an eight-year-old boy with short, unkempt dark brown hair and brown eyes. He lives in New York City with his parents and habitually sneaks pies at night against his mother's wishes, a habit potentially linked to his frequent nightmares. His constant companion is Icarus, a fiercely loyal flying squirrel whose barely comprehensible vocalizations are screechy and squirrel-like. Nemo's recurring dreams transport him to Slumberland, a fantastical realm where King Morpheus summons him to be playmate to Princess Camille and heir to the throne. He first arrives wearing a distinctive white-collared sleeping jumpsuit fastened with one button. Later outfits include a royal blue military uniform adorned with gold buttons for his coronation and a sailor-style shirt with a red neckerchief during travels. King Morpheus entrusts Nemo with a golden key shaped like a dragon, capable of opening any door in Slumberland but forbidden to unlock one specific door bearing a dragon insignia. Tempted by Flip, a mischievous green clown, Nemo disobeys and opens the forbidden door. This releases the Nightmare King, embodiment of nightmares, who captures Morpheus. Nemo immediately feels profound guilt, recognizing his responsibility. As Slumberland faces peril, Nemo is given the royal scepter—the only weapon able to defeat the Nightmare King. His initial attempts to use it fail due to forgotten incantations, causing him to awaken repeatedly before re-entering the dream. He demonstrates compassion by befriending the maligned Boomps, shape-shifting goblins, a decision that later proves crucial as they help him reach Nightmare Castle. Nemo evolves from a naive, easily influenced child into a determined hero. He leads a rescue mission through terrifying Nightmare Land. In the climactic battle, he overcomes his fears, successfully recites the scepter's full incantation, and destroys the Nightmare King, seemingly sacrificing his own life. King Morpheus revives him, commends his courage, forgives his transgression, and permanently ends Nemo's nightmares. His relationships deepen: he forms mutual affection with Princess Camille after initial reluctance about interacting with a girl, maintains a complex dynamic with the self-serving Flip, and shares a deep bond with the ever-defensive Icarus. Returning home, Nemo displays newfound maturity by apologizing to his mother for stealing pie.