The movie begins with a dark and gloomy scene where the film’s antagonist, Zirconia, the right-hand servant of queen Nehelenia, has evil intentions toward the Earth. The scene then shifts to a sleeping little girl named Chibiusa waking up from her bed and finding out that today is the day she’s supposed to return to the 30th century. She soon finds herself in the future, waiting to watch the solar eclipse with Usagi, Mamoru, and Diana.
Meanwhile, the inner solar guardians are also eagerly waiting for the solar eclipse, and while waiting, they hear a bell. Suddenly all three receive a vision from a Pegasus asking for their help. As soon as the Pegasus disappears, Mamoru feels a stabbing pain in his chest. Once the event begins and the sky gets darker, the Dead Moon Circus arrives on a flagship during the eclipse’s peak. Their pompous entrance disappears as the light returns, leaving Chibiusa, Usagi and Mamoru confused. Meanwhile, the Inner Sailor Guardians, who saw the same announcement from the Circus, were also left perplexed about what had just happened.
Mamoru suggests to Chibiusa the park has too many people and is not safe for her to use her Space-Time Key to go home, so for the time being, they explore the town, and while exploring, they come across Dead Moon Circus’ signs. As Mamuro and Usagi are bewildered regarding the signs, Chibiusa gets distracted by the Kaleidoscope and persuade Mamoru to buy them matching kaleidoscopes. Because it is still crowded in the park, they decide to have a sleepover at Mamoru’s house. Chibiusa chooses to wait till tomorrow morning to go back to the future, and while they are about to sleep, Chibiusa mentions that Neo-Queen Serenity would tell her bedtime stories such as an empire that sunk in the sea, the mystery of pyramids, the cursed diamond and dark world inside a mirror that appears on the nights of a new moon.
Shortly afterward, Chibiusa and Usagi have a minor disagreement about envying and wishing they had each other’s age.
Meanwhile, at the Dead Moon Circus, Zirconia sits on her throne in front of a tiger, hawk, and fish. Her servant (JunJun, VesVes, CereCere, and PallaPalla), known as the Amazonessess, appear, and PallaPalla uses an Amazon Stone to conjure a dark barrier around the city where the Circus is. That night while Chibiusa is fast asleep, she dreams of riding a Pegasus across the city. While mesmerized by the view, she also notices the barrier spelled upon the Juban Shopping District by PallaPalla and that His name is Helios, and he needs the Golden Crystal. He also wants her to lend her powers to save Elysion and gives her a bell, instructing her to ring it if she ever needs to summon him. When Chibiusa wakes up early to head back to the future, she thinks it was all a dream, but she changes her mind once the bell slips out of her clothes. She leaves Mamuro’s house with a note telling them she left to go back to the future; however, when Chibiusa tries to go back to the future, she is unsuccessful as PallaPalla’s barrier keeps Chibiusa and Diana from returning to the 30th century. PallaPalla senses the disturbance on her barrier, finding out that someone has tried to break it, and VesVes sends the tiger into the city to find the person responsible for it.
Chibiusa sees the vision of Helios as desperate for help and decides to help him along with Usagi, Mamoru, Luna, and Artemis. So, they head for the command center. While in the center, they hear news about a tiger that has escaped from the Circus. After hearing the news, Usagi and Chibiusa leave. Meanwhile, Mamuro feels the same stabbing pain. Unfortunately, Usagi and Chibiusa find themselves unable to transform. While both are distressed about their situation, their Holy Grails appear, allowing them to again transform into Super Sailor Moon and Super Sailor Chibi Moon but without weapons. However, before they can stop the tiger, VesVes and PallaPalla arrive; VesVes sends the tiger back to the Circus, and PallaPalla summons nightmare creatures called Lemures to attack Sailor Moon and Sailor Chibi Moon, but due to possessing no weapons, they are unable to defend themselves against the Lemures leaving no choice Chibiusa summons Helios with the bell to give them guns. He transforms their kaleidoscopes into their new magic weapons: the Moon Kaleidoscope and the Chibi Moon Kaleidoscope. These weapons enable them to destroy the Lemures and PallaPalla’s Amazon Stone, and after being defeated, PallaPalla and VesVes disappear from the plot. PallaPalla uses a mirror to read Usagi and Chibiusa’s thoughts and switches their ages, while Zirconia’s eyeball servant, Zircon, spies on them, while Mamuro faints again.
On the other hand, queen Nehelenia reminds Zirconia of their agenda. She discusses their evil intentions of destroying their sworn enemies, the White Moon Kingdom, and stealing the Legendary Silver Crystal. The scene then shifts to Minako, Ami, Rei, and Makoto meeting the girls in the hospital who have brought Mamoru after he fainted for an unknown reason. Ami’s mother (who is Mamuro’s doctor) makes Mamuro undergo specific examinations, and the cause of his illness is determined to be an unusual shadow in his lungs. Mamoru heads home to rest, whereas Usagi and Chibiusa are still age-swapped. Helios appears before Chibiusa again and believes she is the chosen maiden he is looking for, but she is unsure about that. Ami is stressed as her parents are divorced. She lives with her mom and is a responsible daughter; however, she still misses her dad.
The plot is again focused on PallaPalla, who uses more Amazon Stones to turn the tiger, the hawk, and the fish into humans named Tiger’s Eye, Hawk’s Eye, and Fish Eye. Fish Eye volunteers to go first and targets Ami as they both are made up of water elements. He opens a tropical fish store which Ami enters, and PallaPalla pretending to work there persuades her to buy a fish that is Fish Eye in his animal form. Ami thinks about her mother and father as she tries to investigate the new enemy on her computer.
Later that night, Fish Eye sends Lemures to Ami’s home to make her experience a nightmare of her mother and everyone around rejecting her. When Ami resists and calls Usagi for help, Fish Eye pulls her into a mirror to stay in a peaceful underwater setting forever. As she falls into the nightmare, Guardian Mercury reminds her of her true dream. Many people care about her helping her resist and transform into Super Sailor Mercury and using Mercury Aqua Rhapsody with her Mercury Harp to break out of the mirror. Usagi and Chibiusa arrive and transform, regaining their original ages, and together they destroy Fisheye in the process.
Chibiusa still doubts herself as the maiden after comparing herself to Usagi (Sailor moon) and tells Helios about Usagi. Helios then learns that Usagi is Princess Serenity, beside that, Helios is revealed to be astral projecting from a cage in Elysion, which has been corrupted and caged by Nehelenia, who taunts Helios from her mirror. A day before the Dead Moon Circus opens, Rei questions her dream to run Hikawa Shrine in her Grandpa’s place and is unsure of herself. When the Dead Moon Circus opens, everyone splits into groups to check it out. Rei is lured into a Mirror House by PallaPalla, where she is attacked by the Lemures giving her a nightmare, and she falls into the mirror but is saved by Phobos and Deimos, who break into the Mirror House, and she transforms into Super Sailor Mars. In the meantime, the Amazoness Quartet performs at the main circus tent and has more Lemures drain energy from the crowd for Zirconia to “revive” Nehelenia.
While Rei breaks the spell of Amazonness, It is shown that Mamoru’s health is worsening, and Helios is protecting him. It is then revealed that Helios is a priest of Elysion, a sacred place deep within the Earth that covers it. Helios is also Mamoru’s guardian priest, and they are connected to the Earth and Elysion within it. The cause of Mamoru’s illness is revealed to be a black rose in his and Helios’s chests, a sign of the curse that Nehelenia did. The plot then focuses on other inner solar guardians who are attacked one by one by the Lemures. However, their guardians helped each of them to overcome the nightmare and hallucinations and allowed them to transform. Soon after the Super Sailor Senshi reunite, PallaPalla traps them in vines before confronting them alongside VesVes, CereCere, and JunJun.
The movie ends As Usagi falls sick from a Black Rose inside her at home while Chibiusa watches. And the post-credit scenes depict suspense yet Zirconia uses the nightmare energy; she has accumulated to summon a giant moon of darkness above the Circus. So, does this mean that the story is still ongoing?
