A woman’s voice talks about space and what scientists say about it. She says they know nothing about the space dog who chases comets and rolls in stardust. The space dog takes a bite out of the moon almost every night and that explains why the moon has phases. And when it’s a full moon, it’s the moon goddess Chang’e who has made the space dog spit out the bite. A woman and her kid giggle at her story and a man cuts in. He offers to give the scientific explanation but the young girl says she’ll stick to her mommy’s explanation. The girl requests for the story of the moon goddess again and her mother gives in.
Long ago, Chang’e and Houyi were in love. A magic potion Chang’e took made her float away, leaving behind her true love. She lives and waits for him on the moon above, and has only the jade rabbit by her side. After Houyi died on earth, Chang’e cried and the tears turned into stardust. The little girl asks her father if he thinks the story of Chang’e is real and he says yes. The little girl is flying a rabbit rocket on the streets. Her parents, in their little pastry shop, tell her to slow down and help them make moon cakes. The girl is excited and practices beside her mother as the older woman watches. While watching the preparation and selling process, the little girl grows a few years older. Her mother is now sick. By the river, where the story began, the little girl is given a tiny rabbit as a present by her parents. Her mother dies shortly after.
Four years later, the girl, Fei Fei, makes an offering of a mooncake to her mother. The rabbit is now grown and follows her to make deliveries of mooncakes. It is the Moon festival so the atmosphere is exciting. She makes a stop at a train construction site and chats excitedly about magnetic levitation. Fei returns home to find out that the guest her father’s expecting is Mrs Zhong and they seem close. Mrs Zhong has convinced Baba, Fei’s father, to use dates in the mooncake recipe and this upsets Fei. While she tries to clean the mess Mrs Zhong made in the kitchen, Chim leaps over her with his pet frog. He is Mrs Zhong’s son. At dinner, Fei gets teased by her aunties about her belief in Chang’e. Even Baba seems to no longer believe in her. She learns that he would marry Mrs Zhong and runs to her room.
The moon shines brightly into Fei’s room. Bungee, the rabbit, jumps into the streets and Fei goes out looking for her. She finds Bungee at the river bank where she spent time with her mother. She sees Bungee and a bird staring at each other. She breaks down, gazing at the moon, and calling on her mother. She decides to build a rocket to fly to the moon and make Baba believe she’s real, so that he’ll remember her mother. All her efforts fail until she decides to use magnetic levitation but Chin gets on the rocket without her knowledge. They’re a few meters from the moon when the rocket stops and starts falling back. They’re yelling their lungs out when everything stops and a beam of green light pulls their vehicle to the moon. Their rocket suddenly gets attacked by space lions and they’re kicked off the beam of light and onto the surface of the moon.
They’re knocked out from the fierce landing. The space lions pick them up from the wreckage and take them to a magical place. Talking mooncakes roll out and drag them into a dark empty place. They hear a lady’s voice and soon, Chang’e reveals herself, singing in a beautiful voice, and entering a massive crowd of magical forms. After the performance, Chang’e asks for her gift but Fei has no idea what she’s talking about. Chang’e gives in to Fei’s request for a photo but refuses to give her the photo if she doesn’t have her gift. The gift is what will bring Houyi back to Chang’e. She announces a competition in the whole of Lunaria—the name of the kingdom. She promises to grant the wish of whoever brings her the gift before the last dust of the moon falls away and all hopes of bringing Houyi back are lost.
Chin tries to offer Fei his help but she rejects him. He tells her they would be siblings but she tells him that that would never happen. That hurts Chin and Bungee runs off with him. Fei hitches a ride with a bunch of magical chicks. She lies to the lead that she knows where the gift is so that he’d let her use his bike. Chin is sulking. He says he’ll be a great brother and Bungee seems to agree with him. He sees a line of mooncakes marching inside. Their leader is holding the photo of Chang’e and Fei. Chin decides to bring the photo to Fei to prove his worthiness of her as a sister. He charges at the mooncakes but magical algae looking forms appear out of nowhere and come after him. He tries to touch them but they’re charged with electricity.
Chang’e shows up and dismisses the forms — she calls them palace security. When asked why he was in the palace, Chin says he wants the photo for Fei. Chang’e reminds him that they can only get the photo after giving her the gift. Chin says he knows where the gift is and is dragged to the interrogation room. Chang’e says they’ll play a game of table tennis and the winner gets either the photo or the gift. Against all odds, Chin wins the game but Chang’e walks away in anger and locks Chin in the interrogation room. Chang’e tells her attendants that they’re running out of time. The mooncakes try to calm her down with yoga but Chang’e ends up crying and causing a meteor shower. She asks the jade rabbit if the potion is working but his ears drop. Chang’e flares up and causes terrible storms.
Meanwhile, the meteor shower has caught up with Fei and the chicks. The chicks want to turn back since going on with the mission with the current weather situation was suicide. However, Fei says they continue and help them drive through the storm. In the interrogation room, Chin is still stuck. He keeps trying to run through the doors but his pet frog tells him to give up. Fei and the chicks have arrived at the wreckage site. She finds Gobi there. He talks so much and annoys Fei. He is Chang’e’s adviser and he was kicked out of the palace according to the Lunarian Chickens. Fei manages to get them off his back and they joke around. Fei sees her Chang’e doll and decides it must be the gift Chang’e has been looking for. She excitedly shows it to the chickens and they take it from her and run off to the palace without her.
Fei is without a bike or vehicle to bring her back to the palace. After much nagging, she agrees to let Gobi help her find her way back to the palace. Meanwhile, Bungee follows the jade rabbit into a flower hole and watches him work on the potion. It doesn’t work out and she gives out her hideout by mistake. The bowl for the potion is about to fall off because the jade rabbit was startled. Bungee steps in and stops the bowl from falling just in time. She climbs onto the same space as the jade rabbit and he sways, tipping off something on the next elevated space. Sparks fly and hit Bungee’s ears. She loves the transformation and rubs her nose against the jade rabbit’s nose. The affectionate act produces sparkles that fall into the potion bowl and it seems to work now. Bungee walks away and the jade rabbit works on the rest of the potion.
Fei and Gobi are still on the long walk back to the palace. Gobi is talking nonstop and gets tongue tied. He rolls off and lands on lower ground on the moon. Magical flying frogs are awakened and they try to feed on Gobi and Fei. Fei uses Gobi’s long tongue to latch on to a frog’s head. They settle there and hope to get to the palace faster. Gobi tells Fei about the reason he was exiled. He sang a song that upset Chang’e. Fei is disappointed that she’s the opposite of everything her mother said but Gobi explains that she changed when Huoyi died. Gobi says he sang a song about her change and she disappeared — a period they call the great darkness.
Gobi sings the song he sang to the queen. It’s a song about taking in the world, about letting go of the past, and about letting your heart grow, so you can glow. Fei sees the chicks at last. Gobi tries to snatch the doll with his tongue but he only makes the chicks aware of their presence. Fei struggles but fails to get the doll back. She tells Gobi all about the plan to stop her dad from getting remarried. She decides to eat the mooncakes Mrs Zhong gave her and bites glass. She discovers an amulet and brings it to Chang’e. It is the gift she has been looking for. Chang’e puts the pieces of amulet together and Huoyi appears again. However, he soon leaves saying he cannot stay and that Chang’e needs to move on. She breaks down and the great darkness returns.
Chang’e has locked herself up in darkness and no one can penetrate. Fei, however, walks through the barrier even with the knowledge that she might not come out alive. Fei sees her own past with her mum and ends up falling into sadness. Chang’e comforts Fei and convinces her to accept the love that’s around her. Bungee tries to break the barrier but it’s no use. Chang’e tells Fei to move on and assures her that her mother’s spirit will always be with her. Chin breaks through the barrier at that moment and they decide to go home. Chang’e says it’s too late for her since Huoyi isn’t returning but Fei shows her all the love of Gobi and the mooncakes around her. She sings the ending part to Gobi’s song and assures Chang’e that Huoyi’s spirit is always with her. Gobi, the mooncakes, and all of Lunaria gather around Chang’e for a group hug. The Lunaria kingdom lights up once again.
Fei says goodbye to the Lunarians. Chang’e hands her the picture. Fei lets Bungee stay with the jade rabbit and says goodbye to Gobi. The flying space lions lift Fei and Chin and fly them to earth. The picture dissolves. They make it back to earth and Fei piggybacks Chin all the way home. She sees her father waiting for her and it warms her heart. The scene has progressed and Mrs Zhong and Baba are now married. Chin and Fei get along well and it is time for another moon festival. The family has gathered as before and this time around, the mood is cheerier. Fei smiles warmly as they chatter about Chang’e and listens fondly to Mrs Zhong’s family lore about mooncakes. Baba sits at the river bank with Fei. He mentions that she laughs just like her mother and they laugh together. He leaves before her and Fei watches the moon. She looks at her scarf with Chang’e’s picture on it and spots the same bird from the other night when Bungee ran off.
They share a knowing smile and the bird pats her on the head and flies away. Chin interrupts the moment and plays catch with Fei. She doesn’t fight back, but plays along.