Elena arrives in the courtyard with flowers for the parade float she is making with Isabel for Carnaval, a celebration that had been previously banned by Shuriki after she took over Avalor. As she enters, Esteban playfully surprises her by jumping out while wearing the beak of the phoenix they were putting on the float. Elena is happy to see her cousin in such a good mood and comments on it. As Esteban helps her pick up the flowers she'd dropped, Elena reminisces about the Carnival fourty-one years ago. Esteban comments that one of his last happy memories before Shuriki's rule was riding in the parade with Elena and her mother. Elena states she's bringing back the Carnival in order to make new happy memories.
As they continue to build the float, Isabel is surprised by Esteban's jokes since he's always so serious. Inspired by his joy, Elena asks Esteban if he would like to be the King of the Carnival. Esteban politely refuses the offer, unsure if he is worthy of such an honour. Armando suddenly drops the phoenix beak onto Esteban's head. When Esteban opens the beak, he is greeted by Victor Delgado, a childhood friend of his who has entered the palace ground with his daughter Carla. Victor teases Esteban by calling him his patronizing old nickname "El Segundo" before embracing him and making a snide remark only Esteban can hear about something that Esteban did to him fourty-one years ago. Victor re-introduces himself to the Flores family who can't recall him. Throughout his childhood, Victor spent time in the palace while his father served as treasurer to King Raul and Queen Lucia. They remember him and greet him fondly, as Victor hugs Francisco, Esteban comments that Victor had stolen his grandfather; broach. Francisco and Luisa laugh, remembering how Victor and Esteban would always be doing their 'slight-of-hand' tricks to get things that didn't belong to them. Victor returns the broach and explains that for the last fourty-one years he'd been living elsewhere since Shuriki had kicked them out of Avalor. He now claims that he has returned to show Carla where he grew up and celebrate the first Carnival in decades. Esteban is skeptical of this explanation but Elena invites them to be guests of honour in the parade to which they agree. Carla then asks to have a tour of the palace.
During the tour, Victor teases Esteban about his nickname, saying he was given it since he always came in second during their races through the palace halls. Carla asks to see where her grandfather worked and the group go to see the treasury. Elena points out the special tiara that her mother wore only during Carnival. However, they can't see it up close since the room is completely rigged with booby traps. As they head back to help Isa with the float, Carla hands her father the treasury key that she had taken off the guard. She goes back to the courtyard to distract the royal family while Victor asks to rest in the parlour. Esteban asks Higgins to follow Victor.
Victor realizes he is being tracked and easily outsmarts HIggins into getting him some food before continuing to the treasury. There he sets off a booby trap that hits him with purple powder. Realizing he won't be able to pass all of the traps, Victor angrily heads back to the courtyard. There, he is confronted by Esteban who sees some of the powder on his sleeves. As Esteban accuses Victor of stealing from the treasury, his old friend turns the tables back on him. Victor reminds Esteban about the deal they made with Shuriki together. All three of them would rule Avalor with Victor and Esteban helped her invade the kingdom. However, when Shuriki turned on Victor and threw his family out, Esteban didn't do a thing. Esteban argues that he didn't have a choice and feared for his life after seeing what happened to his uncle and aunt. Victor ignores him, claiming that he always had a choice. He then threatens to reveal the details of this deal with the royal family unless Esteban steals the jewels and tiara for him.
Esteban takes the key from Victor and makes his way to the treasury nervously. As he skillfully dodges the traps without any problem, he worries about stealing the jewels but decides that it would still be better than having his family know that he was responsible for Shuriki's invasion. As a teenager, Esteban didn't understand how much his family truly loved him but now he feels he must steal in order to protect his secret since it would tear his family apart. Esteban claims that hurting his family is something he could never do again. Sadly, he leaves the treasury with a satchel full of the jewels and the tiara.
As he leaves, he's stopped by Elena who sees the tiara. Esteban quickly lies and says that he brought it for her to wear and that the rest of the jewels are for the family so they don't feel left out. Elena puts on the crown and Esteban is taken aback by how much she looks like her mother in it. Elena kisses him on the cheek and thanks him before taking the satchel of jewels to the family.
In the courtyard, Carla sees that Elena has the jewels and is handing them out to the family. Victor confronts Esteban and tells him to use their slight-of-hand tricks to take the jewels off while he creates a diversion. While in the float, Victor makes the horses run through the town causing the family to toss around in their seats. Esteban helps his family, secretly sliding off the jewels in the process. However, Elena sees the beak coming loose again and heads up the neck of the phoenix. Esteban tells Victor he's unable to take the tiara with the whole family seeing and Carla unhooks the seats from the float, causing Francisco, Luisa, and Isabel to crash in the park.
Carla chases Elena, who now realizes their plan, up the neck of the phoenix. Esteban tries to convince Victor to just leave with what he has, but Victor claims the tiara is the only piece that matters. Esteban takes the reins of the horses and pulls the float to a stop. Victor threatens Esteban again and tells him that he will tell Elena everything about Shuriki and the deal. Esteban refuses to help him any more and accepts the outcome. Victor laughs and calls up to Elena, revealing the whole story about Esteban's secret deal. As Elena processes the story, Carla steals the tiara from her head before she and her father throw Esteban and Elena into the inner compartment of the float, trapping them inside the phoenix. Victor and Carla then take the jewels and the horses to ride out of Avalor.
While in the float, Elena tells Esteban not to worry since she believes Victor was lying in order to distract her. Esteban, realizing her misunderstanding, goes along with it, but tells her he still feels guilty about serving Shuriki. Elena says she understood he did what he had to do to survive and reminds him that he played a big part in defeating her. She then explains that he can't change his actions from the past and can only control what he does in the present. Esteban considers this and realizes that his cousin is right and that he can only change his future not his past mistakes. They figure they can chase the Delgado's with the float and Elena climbs up the inside and looks out of the beak hole while Esteban hits the walls inside to steer them down the hill. They soon catch up with Victor and Carla. The townfolk notice the chase and run to their aid. Esteban and Elena catch up to Victor and Carla in the park where they are thrown from their horses. As they try to run away, they're caught by the townsfolk and the royal family. Once again the Delgado's are thrown out from Avalor. While being taken away, Victor claims that Avalor has not heard the last of them.
Esteban returns the tiara to Elena and Isabel gives the Carnival crown to Elena who then crowns her cousin as the King of the Carnival. Esteban announces the official re-starting of the Carnival parade and the townsfolk cheer.
The image gallery for King of the Carnaval may be viewed here.