Continuing from where "Destinies Collide" ended, Cassandra reveals what she saw while inside the House of Yesterday's Tomorrow (during "Rapunzeltopia"). She had met a disembodied spirit who showed her a vision of her past. From this vision, Cassandra learned that she was the biological daughter of Mother Gothel, who abandoned her on the night she kidnapped Rapunzel. Convinced by the spirit that Rapunzel had been overshadowing her for the entirety of her life, and no longer wanting such a destiny, Cassandra has stolen the Moonstone and declared Rapunzel's destiny as her own. Even though she is confronted by Adira, who ordered her to give up the Moonstone, Cassandra easily repels the warrior away and steals her Shadow Blade. As the Black Rocks cover her, Cassandra escapes from the group, despite Rapunzel's pleas not to cross the line, and severs all ties with them, with Rapunzel devastated over the recent turn of events.
With Cassandra gone, Rapunzel, in a surprisingly cheerful attitude, tries to focus on a method of returning home to Corona, while Eugene suspects that she is in extreme denial over Cassandra's betrayal. Just then, the group spots a balloon flying their way, and it is revealed to be piloted by Ulf. With Shorty translating, Ulf informs them that Corona is in danger, and Rapunzel realizes they need to return immediately. With King Edmund and Adira deciding not to accompany them, Rapunzel and the others board the balloon and fly back to Corona, while being watched by Cassandra and Owl.
Upon arriving in Corona, the gang discovers that the kingdom is nearly deserted, save for Feldspar, who is mumbling to himself about a new order from King Frederic to mine unusual green crystals. Upon hearing this, Rapunzel and the group head for the castle and meet up with the King and Queen. But to her shock, King Frederic and Queen Arianna have no memory of who Rapunzel is. A moment later, Andrew arrives with the Separatists of Saporia, declaring that Corona will soon be under their control. He also reveals that he has forged an alliance with Varian, who reveals that the Separatists have used a Saporian Wand of Oblivium to erase the memories of the King and Queen. He next reveals his plan to harness the power of the wand and create a synthetic gas that will erase the memories of everyone in Corona, and he has dubbed it "Quirineon" in honor of his father. Not wanting this plan to be carried out, Rapunzel leads the charge against the Separatists, but thanks to Varian's chemicals, our heroes are easily outmatched. At Eugene's suggestion, they retreat with the Separatists in hot pursuit.
With our heroes having suffered defeat at the hands of Varian and the Separatists, they try to find a safe place to hide until they can formulate a plan. Just then, Xavier reveals himself along with other citizens that had not left the city. Xavier reveals that the King had ordered all the subjects to the mine to excavate crystals for Varian's chemicals. They wanted to rebel against this order, but doing so would be an act of treason. However, Xavier states that now that Rapunzel has returned, they have a chance to save all of Corona. Unfortunately, Rapunzel does not feel confident enough that she can lead them to victory. Xavier promises to give her time to think about it.
While Rapunzel works on a new frying pan to replace the one destroyed in the previous battle, Eugene notices the look of anger on her face and tries one more time to talk to her, saying that she's not alone in dealing with Cassandra's betrayal. Rapunzel agrees with him, just as Xavier asks her to come join the others in formulating a plan. She promises to be there, but then ventures out on her own, returning to the castle and being secretly followed by Pascal.
Meanwhile, Varian is working hard to perfect his Quirineon formula, but the ensuing result is a powerful explosive. The Separatists decide to use the formula in its current state, as Andrew feels it can be more useful as it is now.
Using stealth, Rapunzel and Pascal make their way through the castle and manage to avoid several of the Separatists until they reach Cassandra's room, where she is reminded that her best friend is no longer her best friend and finally breaks down over the recent betrayal. But then, she is captured by one of the Separatists and thrown in the dungeon.
As Rapunzel reasons with Varian that the kingdom was in danger by the blizzard and her people needed her, the sun drop in her hair did not work, she could not do anything to the amber and that she didn't mean to break her promise to him and reminds him they were friends and wants to be friends with him again, he reveals his true feelings and his belief that no one in Corona will forgive him for his past misdeeds, so he wants to make everyone forget about them completely and gain back their trust and become friends again with Rapunzel. Rapunzel says how could he be so sure if he don’t give them a chance, Varian points some of his actions that he took Queen Arianna prisoner, threatened Rapunzel and helped the Separatists to take over Corona. However, Andrew reveals that there has been a change in plans: They plan to use the Quirineon Varian created to destroy Corona instead. Upon discovering the double-cross, Varian tries to take back control of the situation, but throws the wrong chemical and soaks the Separatists in soap. He is subsequently thrown in the cell along with Rapunzel and Pascal.
With Rapunzel and Varian alone together, he tells her that he knows that his father would be ashamed of him. She tells him that she knows how feeling betrayed when someone you trust let you down, and Varian says he thought if he could make her forget everything that happened, they could become friends again and learn to trust again. Suddenly, Eugene and Lance arrive, with the former having discovered that Rapunzel had gone off on her own. After being freed, Eugene is reluctant by telling Rapunzel that after everything Varian has done to everyone, she convinces her rescuers to allow Varian to join them in saving Corona, just as Andrew is sending the King and Queen away from the kingdom, locked in the royal coach, before the Separatists implement their plan.
Rapunzel sends Eugene and Lance to follow the coach while she and Varian concentrate on thwarting Andrew and the Separatists before they can use the Quirineon to destroy Corona. The twosome discover a giant airship and deduce that the Separatists plan on dropping Quirineon on the city from the air, like bombs. Rapunzel and Varian stow away just as the airship takes off, and Andrew drops the first of the bombs from the deck. However, thanks to Rapunzel's hair, they are able to catch the barrel before it can fall out of reach and explode. Then Rapunzel and Varian get on deck, and she battles the Separatists while he disables the ship and jettisons their enemies. However, they are losing altitude quickly, and if they crash, the Quirineon will explode and destroy the city anyway. Varian has an idea on using the Quirineon to give the disabled airship more altitude so that it will explode out of reach of Corona. He volunteers to do the deed himself, as atonement for his misdeeds, but Rapunzel, knowing that the ensuing explosion will kill him, suddenly jettisons him off the airship after regretting for leaving her kingdom helpless and turns the propane on the Quirineon, causing the ship to rise as she prepares to fix her one mistake.
Meanwhile, as Kai is driving the royal coach further away from Corona, Lance and Eugene are having trouble unlocking the doors, as Eugene has lost his lock pick in the commotion. Eugene realizes they need the original key to unlock the door, and distracts Kai onto the roof of the coach, while Lance tries to rein in the horse pulling, only to snap the reins loose. Eugene orders Kai to hand over the keys, but Kai refuses. On this, Lance ties Kai up in the severed reins and sends the freed horse running off and dragging Kai behind him, but forgets to grab the key. The runaway coach eventually is sent toward a cliff, but is saved from going over by Maximus and Fidella. However, Kai is not so lucky, as he is pushed off the cliff, and the King and Queen get out of the carriage, unaware of what just happened.
Back at the airship, Rapunzel feels she has gotten it high enough to be out of harm's way and uses the remaining propane to detonate the Quirineon, while using her hair to shield herself and Pascal from the blast. As she falls back to the ground, she uses her hair to swing off a ledge and land safely. Rapunzel and Eugene share a hug in the wake of their toughest victory yet, and she tells him there's still a broken promise she must fix.
Inside Varian's home in Old Corona, Rapunzel tells him that she discovered something during her journey and prepares to make one last attempt to free Quirin from the amber where he is imprisoned. She has Varian prepared with a bucket of water and asks him to snap her out of it, in case her attempt does more harm than good. She begins to chant the Decay Incantation, which slowly melts away the amber, but cannot stop chanting it, and the water Varian splashes her with has no effect. Varian tries to shake Rapunzel awake, only to have his gloves dissolved on contact. Believing in Rapunzel for not giving up on him, he declares his refusal to give up on her, and this stirs her awake, causing her to collapse onto her knees. The two hug before Varian cries and embraces his father, overjoyed to know that he is finally free and still alive. Just then, Varian notices the note his father wrote has dissolved along with the melted amber, and he asks his father what was written on it. Quirin simply states that the note said that he was proud of his son, and always has been.
With Corona safe for now, and King Frederic and Queen Arianna still without their memories, Rapunzel becomes acting Queen in their place, and the entire kingdom celebrates a new beginning for itself. In the end, Rapunzel decides to finally open up to Eugene about Cassandra.
- Mandy Moore as Rapunzel
- Zachary Levi as Eugene Fitzherbert, Feldspar
- James Monroe Iglehart as Lance Strongbow
- Eden Espinosa as Cassandra
- Hudson D'Andrea as Little Cassandra
- Jeremy Jordan as Varian
- Clancy Brown as King Frederic
- Julie Bowen as Queen Arianna
- Adewale Akinnuoye-Agbaje as Xavier
- M. C. Gainey as Captain of the Guard
- Jonathan Banks as Quirin
- Bruce Campbell as King Edmund
- Kelly Hu as Adira
- Steve Blum as Attila
- Paul F. Tompkins as Shorty
- Donna Murphy as Mother Gothel
- Dean Winters as Andrew
- Jennifer Veal as Enchanted Girl
- Betsy Sodaro as Clementine
- Khary Payton as Kai
- Richard Kind as Monty
- Clips from previous episodes are played during the beginning of the episode: "Secret of the Sun Drop", "Beyond the Corona Walls", "Rapunzel and the Great Tree", "Mirror, Mirror", "Rapunzeltopia", "lost and Found" and "Destinies Collide".
- Shorty is revealed to be fluent in miming, able to translate Ulf.
- Maximus and Pascal chasing after Rapunzel's Crown is a reference to the future events of Tangled Ever After when they chase after Rapunzel's and Eugene's wedding rings.
- Starting at the end of the episode, Rapunzel and Eugene wear brand new signature outfits for the third season.
- This is the second time Rapunzel and Eugene wear brand new signature outfits during a new season.
- The way Varian was locked inside the cell alongside Rapunzel and Pascal after Varian betrayed the Saporians is similar to the way Eugene was locked inside the cell alongside Cassandra after Rapunzel can't stand the argument of Eugene and Cassandra in "Cassandra v. Eugene".
- Rapunzel's reactions to Cassandra's betrayal is applied from the five stages of grief.
- It is revealed to been one year after Rapunzel and her friends traveled outside of Corona.
- Varian's chemical balls is a reference to Honey Lemon's chemical balls from "Big Hero 6".
- One of the member of Separatists of Saporia, Kai is voiced by Khary Payton, who also voiced Cyborg from Teen Titans and Teen Titans Go! and Wasabi from Disney XD show Big Hero 6: The Series.
- Varian trying to stop Rapunzel from singing the Decay Incantation to free Quirin from the amber parallels the way Cassandra tried to stop Rapunzel from singing the Decay Incantation to destroy the tree in "Rapunzel and the Great Tree".
- It is also for the first time Varian seen without his gloves.
- Varian mentions the events in "Secret of the Sun Drop" as part of his misdeeds, the time when he abducted Queen Arianna and attacked Rapunzel.
- Varian wasn't wearing his goggles when he and Rapunzel got onto the blimp with a barrel of Quirineon. But after Rapunzel told Varian to grab his gear and neutralize the chemicals, his goggles' back on his head.
- Varian is wearing his gloves at the celebration but his gloves are melted off when he touched Rapunzel while she was chanting the Decay Incantation, although it's possible that he had a spare pair.
- The Disney+ subtitles say Varian says "Well, look who we have here," but the voice is too deep to be Varian's.
- February 10-11, 2020 (Poland)
- April 19, 2020 (Brazil)
- January 1, 2021 (Portugal) (Premiere on Disney+)