Corona is preparing a welcoming banquet for the Griffin of Pittsford in the hopes of securing peace between their two nations. Nigel has some concerns, because Griffin is known to be notoriously insecure, but King Frederic is certain the banquet will be in good hands. Rapunzel is preparing a speech, Cassandra is foreseeing preparations for her first security checkpoint, and Eugene is Master of Ceremonies. He plans to open the banquet with a fog show and indoor fireworks, but both Rapunzel and especially Cassandra think it is a terrible idea. Pretty soon, all three of them start to criticize each others plans for the banquet with neither one coming to an agreement. Pascal and Maximus get fed up with their bickering, and Xavier offers them a solution. He gives them an Attitude-Reversing Potion, and advises them to give Rapunzel, Eugene, and Cassandra only one drop each. Pascal and Maximus make a barrel of lemonade, and put in three drops of the potion, when Rapunzel, Eugene, and Cassandra suddenly barge into the kitchen, still arguing. Pascal is startled, and accidentally drops the whole bottle in the lemonade. The three of them decide to help themselves to the lemonade, and after each one has a drink they become the opposite of who they are. Cassandra is overwhelmingly peppy, Eugene no longer feels confident about himself, and Rapunzel is all moody. The potion worked.
Rapunzel, Eugene, and Cassandra do not notice they are acting differently until Stan points it out. They quickly figure out that Pascal and Maximus are responsible for this, and turn to Xavier about it. According to Xavier, the effects of the potion should have worn off by now, but because Pascal and Maximus poured in the whole bottle it will be days before Rapunzel, Eguene, and Cassandra return to normal. However, he does say there is a way to reverse the process, by taking the potion again. To make more, he needs the primary ingredient: the oil from a rare three leafed echo plant. It grows among its two leaf cousin at the top of Mount Saison, which is a two hour trip. Rapunzel, Eugene, and Cassandra do not have the time to go themselves, so they send Pascal and Maximus to get the plant.
The Griffin of Pittsford arrives at Corona Castle, and Rapunzel, Eugene, and Cassandra remain unable to be themselves while still under the effects of the potion. Cassandra is relieved of duty when she cheerfully allows a man into the castle without a proper security check, Rapunzel is acting rude towards the Griffin, and Eugene gets all nervous when he opens the banquet with his fog and firework act. Meanwhile, Pascal and Maximus make it back to Xavier with the plant, but accidentally knock him out. So Pascal and Maximus make the potion themselves, and take it to the castle to give to Rapunzel, Eugene, and Cassandra. However, as they charge into the banquet, Pascal again drops most of the potion into Eugene's fog machine. The machine lets out a huge burst of purple fog into the dining hall. As a result of inhaling the fog, Rapunzel, Eugene, and Cassandra return to normal, but everyone else becomes effected by the potion. Arianna becomes ill mannered, Nigel cannot stop laughing, Pete and Stan start fighting each other, the Captain becomes childish, and Frederic is overwhelmingly tyrannical. The king challenges the Griffin to a fight, and when Rapunzel tries to stop him she is sent to the dungeon with her friends.
While imprisoned, the three of them come to mutual understanding that they have been jerks to each other, and Pascal and Max were only trying help teach them a lesson. Rapunzel states that they are not perfect, Cassandra could have at least shown a bit more compassion, Eugene should have shown some humility, and Rapunzel herself learns she does not have to be so upbeat all the time, and should be more franked when annoyed with things. Most importantly, even though there are things about them that annoy each other they are still best friends. After reconciling, Rapunzel, Eugene, and Cassandra break out of prison and return to the dining hall. The place is booming of chaos. Eugene charms the crowd to safety, Cassandra handles the guards, and Rapunzel tries to get through to her father. When all her attempts to snap him out of it fail, she stands in his way, saying he will have to coldly get pass her to achieve this barbaric venture he is overwhelmed by. Frederic hesitates, and suddenly returns to normal. Once everyone is returned to normal, the Griffin sails home, and a peaceful alliance between the two nations is a success. As for the potion, Rapunzel throws it into the sea, hoping it will never be seen again. However, the bottle floats all the way to Old Corona, and ends up in Varian's possession.
- Mandy Moore as Rapunzel
- Zachary Levi as Flynn Rider
- Eden Espinosa as Cassandra
- Clancy Brown as King Frederic
- Adewale Akinnuoye-Agbaje as Xavier
- Sean Hayes as Pete
- Diedrich Bader as Stan
- Julie Bowen as Queen Arianna
- Jon Polito as Griffin of Pittsford
- M. C. Gainey as Captain of the Guards
- Peter MacNicol as Nigel
- Jeremy Jordan as Varian
- There were scenes, storyboarded by Kaitlyn Ritter, that were cut from the final episode.
- There was going to be a scene where a bird would fly up to Rapunzel's window as the sun came up. The bird would start singing, only for Rapunzel to shut it out.
- A peppy Cassandra would come into the courtroom and set off a party popper cannon. Rapunzel would look on unamused, and Cassandra would skip around a timid Eugene.
- There was going to be an extended version of Varian's scene when he finds the potion.
- Cassandra crying out "Best opposite day ever!" is a nod to Rapunzel's line "Best day ever!" in Tangled.