At school, the students are getting ready for a fundraiser, Vincent wanting to sell enough to win the new laptop that will be given as a prize to the one who sells the most chocolate. Mia and Paula assist Vincent, helping him with the sales. However, Violetta has asked her father to help, and her Girl Posse are helping pile the boxes into the car. Mia's bracelet starts glowing, and rather than report Violetta's actions to the teachers, Mia comes up with a different plan, asking Paula and Vincent to handle it and make sure Violetta's father doesn't leave until she gets back.
Arriving in Centopia, it is nighttime. Mia takes a moment to admire the sight of Centopia at night, before deciding to go look for Yuko and Mo. At the castle, Yuko goes to talk to Mo, who is keeping an eye on the guards patrolling the area. Yuko reminds Mo of a promise they had made to watch the full moon, although Mo is reluctant to go because of his duties. Yuko spots the butterfly from Mia's bracelet, and tries to keep Mo from seeing it, convincing him to come along. Mia reaches the two, and Mo tries inviting Mia along. Mia tells them about the latest riddle, and they see the full moon rising in the distance. Yuko, wanting to spend some time alone with Mo, asks Mia to take over Mo's duties of keeping an eye on the guards, while she and Mo head out to search for the trumptus piece. Mia flies over to Onchao and Phuddle sleeping nearby, seeming to have an idea.
Yuko and Mo fly together under the full moon, Mo commenting that it has been a while since they did this. Yuko suggests they head to a place they haven't been to in a while, and Mia, having woken up Onchao and secretly decided to follow them, follows behind. Yuko and Mo reminiscence on old childhood memories, and Mia feels left out when Yuko and Mo refer to themselves as the perfect team. After Yuko and Mo exit the cave to look for the trumptus piece, Mia briefly considers heading home, before Onchao convinces her to stay, and the two decide to look for the trumptus piece on their own.
Yuko and Mo approach the area near Panthea's castle, and spot what appears to be a rock formation resembling a mask. They decide to take a closer look. Meanwhile, Gargona exits the castle to go on patrol. Mia and Onchao are making their way to the castle. Yuko and Mo have trouble finding the place they saw from the skies as clouds block the moonlight, and Yuko spots a small sprout in the middle of the wasteland. While trying to investigate, she accidentally causes some of the rocks to fall down and trap her and Mo underneath. Mo is unable to the move the rocks, and they decide to call for Mia, Yuko thinking they might not have ended up in their current predicament had she been with them in the first place.
Gargona spots Mia flying on Onchao, while Mia starts to feel concerned due to not being able to see Yuko or Mo anymore, and uses her ring to find them. The rocks are too heavy for Mia to move, and she spots the sprout, thinking up a plan. However, before she can ask Onchao to help her with it, Gargona ambushes them and manages to tie up Mia. Mia tells Onchao to flee, but Onchao decides to fight instead, knocking Gargona aside. Mia tells Onchao to use his powers on the sprout, causing it to quickly grow, and moving the rocks, saving Yuko and Mo.
Yuko and Mo untie Mia, and the three hug. Gargona complains about being stuck on a branch. Mia picks up the lanterns Yuko and Mo brought with them, and finds the stone mask formation they were looking for. Onchao and Mo locate and pick up the trumptus piece, and the group fly back towards the castle. Yuko is about to admit to Mia what happened, but Mia admits she already knows. Yuko then correctly guesses that Mia intended to try to find the trumptus piece before she and Mo did. Mia also reveals that she asked Phuddle to take over the guard duty.
Mia returns to her own world, where the other students begin bringing their own boxes of chocolate to Violetta's car, Paula and Vincent having convinced the teacher that Violetta's father would help look after them while they're making their sales. Violetta's father doesn't object to this, while Violetta is not too pleased with this turn of events.
- Continuity Nod: Mia makes use of her tap dancing skills again during the montage in which she, Vincent and Paula go around selling chocolate.