Each night, young Nemo goes to Slumberland and has adventures and befriends the king of Slumberland, Morpheus. But one night Nemo discovers Nightmare Land, and the evil nightmare king, throwing Slumberland and Nemo himself into danger.
A young boy whose dreams transcend reality is sucked into his own fantasy, which is everything he has dreamed of until he unleashes a century old secret that may not only destroy this perfect dream world but reality itself.—Kadi Lynnith
A young boy named Nemo experiences a nightmare in which he is pursued by a locomotive. Upon awakening the next day, he goes with his pet flying squirrel, Icarus to see a parade welcoming a traveling circus. However, Nemo is unable to see the circus since his parents are too busy to take him. That night, Nemo imitates sleepwalking in an attempt to sneak some pie away, which acts against a promise he had made earlier to his mother, who catches him in the act and makes him run back to his room empty-handed. Upon falling asleep, Nemo is approached by figures from the circus parade. The circus organist introduces himself as Professor Genius and claims that they had been sent on a mission by King Morpheus, the king of a realm named Slumberland. The mission involves Nemo becoming the playmate of the princess, Camille. Although Nemo initially has reservations about interacting with a girl, he and Icarus decide to set off to fulfill his mission after being persuaded with a gift box of cookies from the princess.
Nemo is taken to Slumberland in a dirigible which he is allowed to drive, causing some chaos, and is introduced to King Morpheus. Morpheus reveals that he summoned Nemo to become his heir to the throne. Morpheus gives Nemo a golden key that opens every door in the kingdom and warns him of a door with a dragon insignia that must never be opened. Nemo is introduced to Princess Camille and the pair roam the entirety of Slumberland together. Afterward, Nemo meets the mischievous clown, Flip, who convinces him to ditch his prince lessons, and later angers a group of cops, forcing him and Nemo to hide out in a cave. There, Nemo discovers the door that Morpheus warned him not to open. Flip tempts Nemo into unlocking the door, which unleashes "the nightmare". Nemo rushes back to Morpheus' castle in time for his coronation ceremony, where he is handed the royal scepter, the only thing capable of defeating the Nightmare King, the ruler of Nightmare Land, should he ever return to Slumberland. In the middle of a dance session between Morpheus and Genius, "The Nightmare" reaches the castle and steals Morpheus away. As the partygoers search for a scapegoat, Flip and Nemo accuse each other, though the responsibility goes to Nemo who had the key.
Nemo awakens in his home, which floods with seawater and ejects him into the ocean. Genius discovers Nemo and tells him not to blame himself for Morpheus's capture and that Flip is at fault for tempting him, but Nemo accepts his role in the situation, and pledges to find the King. When the two return to Slumberland, they rescue Flip from being shot out of a cannon because he has a map of Nightmare Land, where Morpheus is currently being held. Nemo, Icarus, Camille, Flip, and Genius set off in a tugboat in search of Morpheus. They are soon sucked into a whirlpool and find themselves in the goblin-infested Nightmare Land. The five come across a group of shapeshifting goblins called Boomps who wish to aid in the quest to rescue Morpheus. The Nightmare King sends a flock of gigantic bats to seize the rescue party. Nemo attempts to use the scepter, but cannot remember the incantation, and awakens in his bed after watching Camille, Flip, and Genius get captured. The Boomps appear in Nemo's room and the group travels to Nightmare Castle by flying through a portal in the sky. However, they are subsequently trapped in the castle, where the Nightmare King demands possession of the scepter, threatening his captives, including Morpheus, to try and force Nemo's compliance. After a fierce battle, Nemo uses the scepter to finally defeat and eliminate the Nightmare King, but seemingly at the cost of his own life as well. As everyone mourns Nemo's death, Morpheus uses the scepter to revive him, and accepts his apology for causing everything, citing that his courage has allowed him to make up for his mistake and become a true prince. As Slumberland celebrates the fall of the Nightmare Kingdom, Camille escorts Nemo home on the dirigible. The two then share a kiss before Nemo awakens in his room, where he apologizes to his mother for breaking his promise and trying to take the pie. Nemo's parents also agree to take Nemo to the circus. Nemo stares out the window as he looks forward to his new day.
