Little Nemo: Adventures in Slumberland (released in Japan as simply Nemo (ニモ, Nimo) and credited in some territories as Little Nemo) is a 1989 Japanese-American animated fantasy film directed by Masami Hata and William Hurtz. Based on the comic strip Little Nemo in Slumberland by Winsor McCay, the film went through a lengthy development process with a number of screenwriters. Ultimately, the screenplay was credited to Chris Columbus and Richard Outten; the storyline and art style differed from the original version. The original soundtrack was penned by the Academy Award-winning Sherman Brothers. The film features the English dub voices of Gabriel Damon, Mickey Rooney, René Auberjonois, Danny Mann, and Bernard Erhard.
The movie was infamous for being in development hell with many people, some of whom worked at Disney and others who worked on Star Wars, some of the people who worked on Looney Tunes, as well as some people who would later found Studio Ghibli, figures such as George Lucas, Chuck Jones, Ray Bradbury, Isao Takahata, Brad Bird, Jerry Rees, Chris Columbus, Ken Anderson, Frank Thomas, Oliver Johnston, Paul Julian, Osamu Dezaki, the Sherman Brothers (Richard M. Sherman and Robert B. Sherman), Hayao Miyazaki (who was working at TMS at the time), and Gary Kurtz being involved with the movie before all dropping out.
The film was first released in Japan on July 15, 1989 by the Toho-Towa and in the United States on August 21, 1992 by the Hemdale Film Corporation. It received mixed to positive reviews from publications including the Washington Post, Variety, the New York Post, the Boston Globe, and The New York Times, earned $11.4 million on a $35 million budget and was a box office bomb, but sold well on home video and has since developed a cult following.
The film opens with the young boy Nemo experiencing a dream where he is taking his bed on a flight and finds a city in the clouds. It turns into a nightmare in which he and the bed are dropped at the turn of a clock tower and are pursued by a runaway locomotive and when he wakes up after his nightmare, he sees that it was all a bad dream. 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 because his parents are too busy to take him. Later that night, Nemo imitates sleepwalking in a failed attempt to sneak some pie, going against a promise he had earlier made to his mother. Upon falling asleep that night, Nemo is approached by figures from the 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 royalty of the opposite gender, 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, before nearly running into a presence called "The Nightmare" and after arriving safely in Slumberland and gets the Attention of a mischievous clown named Flip who has ownership of a Map of both Slumberland and Nighmare Land. Later Nemo is introduced to King Morpheus, who doubles as the circus ringmaster on Earth. 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 and Icarus roam the entirety of Slumberland together. Afterward, Nemo is whisked away by Genius to prince lessons and after sneaking away from them gets involved with Flip, who angers a group of police and forces him and Nemo to hide out in a cave where, 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. Morpheus demonstrates the power of the royal scepter, by saying a set of magic words. Nemo is handed the royal scepter, the only thing capable of defeating the Nightmare King 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 reveal each other responsible for opening the forbidden door, but the blame ultimately goes to Nemo since Morpheus gave him the key.
Nemo then awakens in his home hearing the distant voice of the Morphius before his home floods with seawater and ejects him and Icarus into the ocean. Genius reunites with them and tells Nemo not to blame himself and that Flip is to blame for all that has happened; Nemo refutes this, citing that he's the one who made and then broke his promise to Morpheus to never open the door, and resolves to find and rescue the king. When the three return to Slumberland and narrowly prevent Flip's banishment into outer space by cannon, Nemo forces Flip to reveal that he has a map to 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 as one of their own troupe was left behind at Nightmare Castle.
The Nightmare King sends a flock of fearsome and gigantic goblin bats to seize the rescue party. Nemo attempts to use the scepter, but only remembers two words of the full incantation and awakens in his bed along with Icarus just after watching Flip, Genius, and Camille be captured by the Nightmare King's forces. The Boomps appear in Nemo's room and reunite with a lost member of theirs, who gives Nemo a letter from Morpheus containing the scepter's incantation to defeat the Nightmare King. The group returns to Nightmare Land by flying on Nemo's bed through a dimensional portal in the sky, and after another run in with "The Nightmare" soon reach and infiltrate Nightmare Castle. However, they are subsequently trapped in the castle, where the Nightmare King demands possession of the scepter and threatens Flip, Genius, Camille, and Morpheus, whom are all in suspended animated states, with harm if Nemo doesn't comply. After a fierce battle, Nemo uses the scepter to finally defeat and destroy the Nightmare King and purify his kingdom, though due to Nemo's young age, the use of the scepter's full power inadvertently kills him as well. As everyone awakens in the aftermath and discovers Nemo's lifeless body, they begin to mourn for Slumberland's fallen prince. Morpheus, however, uses the scepter to restore Nemo to life. Nemo apologizes for breaking his promise, opening the door, and causing everything to begin with. Morpheus forgives him, citing that his courage and strong will have 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 and Icarus home on the dirigible. The two then nearly share a kiss, after which 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 with Icarus excited about the day ahead of him.