Return to Oz is a 1985 film which is an unofficial sequel to Victor Fleming's The Wizard of Oz. The film was directed by Walter Murch, a respected editor and sound designer. Although it did not fare well at the box office and received mixed reviews from critics, it has gained a loyal following among fans of L. Frank Baum's original Oz books and nostalgic fans of the 1980's.
In October 1899, six months after returning from the Land of Oz, Dorothy Gale has become a melancholic child who cannot sleep, as she is obsessed with her memories of Oz. This concerns Aunt Em and Uncle Henry, who don't believe her, and are worried she cannot help them on the farm, which is at risk of foreclosure after the tornado. The two decide to take her to see Doctor Worley, known for his revolutionary electric healing treatments. Before going, Dorothy, while looking hopefully for any eggs laid by her favorite chicken Billina (who is not producing), finds a key with the OZ glyph, which she believes her friends from Oz sent to her the previous night by shooting star. Aunt Em leaves Dorothy at Dr. Worley's laboratory under the strict care of Nurse Wilson. As she is taken to have treatment during the onset of a huge thunderstorm, the lab has a blackout, and Dorothy is saved by a mysterious blonde girl who reveals that some patients have been driven insane by Worley's treatment and are hidden in the basement. The two escape the building with Nurse Wilson in pursuit, and then fall into a river. The blonde girl vanishes underwater, but Dorothy survives by clambering on board a chicken coop.
Upon awakening, Dorothy finds herself back in Oz with Billina, who can now talk, for company. The two discover the ruined Yellow Brick Road, which leads them to the Emerald City, now in ruins, missing its emeralds, and all of its citizens including the Tin Woodman and Cowardly Lion turned to stone. Pursued by Wheelers (men who have wheels for hands and feet), Dorothy and Billina hide in a secret room using the key, and meet a clockwork mechanical man named Tik-Tok. Taking charge, Tik-Tok explains that King Scarecrow is missing and has been captured by the Nome King. When the three go to visit a head-exchanging witch named Mombi (who looks just like Nurse Wilson) for more information, they end up imprisoned. While imprisoned, Dorothy, Billina, and Tik-Tok meet Jack Pumpkinhead, a man made of tree limbs with a pumpkin for a head. Jack refers to Dorothy as his mother since she resembles his own creator and reveals he was brought to life via Mombi's Powder of Life. They formulate a plan to escape to the Nome King's mountain. Dorothy steals the Powder of Life and uses it to vivify The Gump, the head of a moose-like animal whose body is made from a sofa, palm fronds, and rope gathered from their surroundings. They escape and fly across the Deadly Desert with Mombi and the Wheelers pursuing underground.
The Gump's body falls apart while airborne and the group lands on the Nome King's mountain. The Nome King brings Dorothy into his domain and argues that the Scarecrow stole the emeralds from his kingdom to build the Emerald City. Dorothy and Scarecrow reunite briefly, but the Nome King turns him into an ornament and hides him among his large collection. The Nome King offers Dorothy's group a chance to locate the Scarecrow, but three guesses wrong and they will be turned to ornaments as well. All meet this fate and with each one changed, the Nome King becomes increasingly human (who looks like Doctor Worley). When it is Tik-Tok's turn, he pretends that his gears have run down, and Dorothy is allowed in to wind him. Before she enters the ornament room, The Nome King reveals to her that he conquered the Emerald City courtesy of her discarded Ruby Slippers. He offers to use them to send her back home on the condition that she will lose all her memories of OZ, but she refuses and goes to find her friends. Tik-Tok lets Dorothy in on his plan—if he guesses incorrectly, she can see what ornament he will be transformed into, giving her a clue as to which one the Scarecrow is hidden as. But as he makes his last guess, there is a bright flash and Dorothy cannot find him.
On her last guess, Dorothy manages to locate the Scarecrow, who was changed into a green ornament. With the Scarecrow back to normal, he and Dorothy begin restoring the others who are all green ornaments. Upon learning this, the enraged Nome King traps Mombi in a cage for her failure and then confronts Dorothy and company in a gigantic, monstrous form. Intent on killing each one of them, he has his minions block off any possible escape route. He then tries to eat them, but Billina (who had been hiding in Jack's hollow head) lays an egg in fright and it falls into the Nome King's mouth. The Nome King drops Jack and he, his minions, and his kingdom begin crumbling to pieces as eggs are poisonous to Nomes. As the palace crumbles and they seem to have no means of escaping, Dorothy finds the Ruby Slippers and wishes for the Emerald City to return to normal and for her and her friends to escape, which they do. At the Emerald City, during a victory celebration, Dorothy spots the girl who had helped her escape the hospital in Kansas named Princess Ozma, Jack's long-lost creator and the rightful ruler of Oz who had been enchanted into a mirror by Mombi. Taking her place on the throne, Dorothy hands over the Ruby Slippers. After Mombi is imprisoned, Ozma then invites Dorothy to visit Oz any time she likes before sending her home, promising that she will check in with Dorothy from time-to-time to make sure that she is all right. Ozma also promises that if Dorothy ever wishes to return to Oz, she will make it so. Dorothy says goodbye to her friends and disappears in a flash of bright, white light.
Back in Kansas, Dorothy is located on a riverbank by her family. Aunt Em reveals that Worley's hospital was struck by lightning and burned down. Dr. Worley was killed in the fire after he had gone back in to rescue his machines. Nurse Wilson is carried away in a prison cart eerily similar to the one Mombi was trapped in. Upon returning to the farmhouse, Dorothy sees Billina and Ozma peering at her through her bedroom mirror. When Dorothy entreats Aunt Em to come to her room to see Ozma, Ozma silently instructs her to keep her and Oz a secret. Dorothy and Toto then run outside and play.