Frederik has invited the class to his annual Christmas party. He and Josefine have become best friends and plan to compete in the party's dance competition together. They have been practicing for months to win the big Christmas gift basket. But Josefine tells Frederik a big secret that will affect the rest of the party.

Josefine's big secret creates so much drama that she and Frederik are suddenly no longer a couple in the dance competition. And not only that, something very mysterious happens that brings the entire class to a standstill.

Frederik has invited Josefine to his home so they can prepare their school presentations. However, that is not Frederik's only plan for the day; he wants to convince Josefine that she should not change schools. But Josefine is harder to persuade than Frederik had expected. And then the day suddenly takes a turn.

The class has to present how they want to make the world a better place. Frederik has not been able to concentrate because his best friend Josefine is changing schools. He shows up for the presentation completely unprepared. Now Frederik has to improvise in front of the whole class, and it gets a slightly different reception from his classmates than he had expected. Both for better and for worse.

Caroline and Frederik try to convince their teacher to let them use the class fund for a joint Christmas. The plan seems to be working, but there is one requirement; everyone in the class must agree to a joint Christmas. But not everyone is equally enthusiastic about the idea. Frederik has to think creatively to get the whole class on board.

Martine and Frederik have gone on a trip to get a Christmas tree for the class. Frederik intends to spend the day convincing Martine to spend Christmas together. But the plan takes a turn when mysterious things happen in the forest.

It's finally December 1st, and the class is about to start their annual wrapping game. But which gifts are good and which are bad? Caroline has to choose first, and the choice doesn't get any easier when a mysterious giant package appears. Who brought it? and what's inside? The questions only increase when the package is opened.

Frederik and Caroline have set out to find out who the mysterious D.O.N. is. Frederik has a clear suspicion, but he needs to find evidence. Caroline believes they can find clues if they unwrap all the other presents. But will Caroline's plan work? And can they even get away with it?

Caroline and Frederik are faced with a real mess, but are saved by Bertram, who has important news; D.O.N. has been at play in the class again. And this time D.O.N. is after one of the students in particular.

"The black squad" pressures Frederik to apologize to Martine for accusing her of being D.O.N. . A series of events causes the two of them to jointly begin to devise a new theory about who D.O.N. could be. And Frederik rushes to tell Caroline about the new theory.

Hoping to expose D.O.N., Frederik has set a trap to catch D.O.N. red-handed. But an argument with Josefine means that he has to put Caroline on the job instead. Will the plan succeed? Or is D.O.N. simply too cunning?

Frederik is convinced that Mathilde is the Evil Santa. And when he is invited to her house with Josefine, he takes the opportunity to sniff around the house for evidence. Will he succeed in exposing Mathilde as the Evil Santa?

Frederik thinks he finally has the proof of who the Evil Santa is. But a text message from his best friend Josefine changes everything, and suddenly the entire class turns against Frederik.

Everyone thinks Frederik is the Evil Santa and for the first time he feels what it's like to be kept out of class. And now Mathilde has gone to the inspector to tell him that Frederik is behind the Evil Santa's vandalism and bullying. What will happen to Frederik if the inspector believes Mathilde?

Bertram and Martine suspect each other of vandalizing the school toilet. Now they fight over who will be the lucky winner. As lucky winner, you get a microphone and the opportunity to expose the other person in front of everyone else.

Christmas Eve is approaching and everyone in the class has brought a dish so they can vote on what will be served for the big night. But Josefine suspects Bertram of knowing something about the Evil Santa. Maybe he knows something that can prove Frederik is innocent.

Mathilde wants to win the planned treasure hunt, but the rest of her team has a completely different mission. They want to find out who is behind the Evil Santa. An unexpected call from the Evil Santa brings them even closer to the truth.

Josefine, Bertram and Martin are desperately trying to find out why the Evil Santa has stolen the money from the class treasury. The Evil Santa will tell them why on one condition; if everyone comes on the cabin trip. There's just one problem: Frederik is furious with everyone in the class and refuses to go.

Bertram, Josefine, Frederik and Martine try to get the class fund back and in that way try to save Christmas together. However, it is not an easy task, as the Evil Santa is constantly trying to scare them and makes new demands.

The Evil Santa has promised to return the class treasure, but it suddenly becomes clear that the Santa has another sinister plan up his sleeve. Now the class tries to stop the Evil Santa once and for all.

The Evil Santa has disappeared from the cabin. In a last-ditch attempt to save the class's shared Christmas, they split up to look for the Santa. Will they succeed in finding the Evil Santa again? And will they succeed in saving their shared Christmas?

The class tries to prepare the nativity play to be shown at Christmas. But when Christmas is canceled and Frederik finds out that he has not succeeded in getting Josefine to stay in the class, Bertram tries to unite the class around a farewell gift for Josefine.

Frederik has planned a mini Christmas together for him and Josefine, but Josefine doesn't show up alone, and Frederik's surprise is ruined. When he finally gets Josefine to himself, they are disturbed, and Josefine is suddenly gone.

It's Christmas Eve. Frederik usually hangs out with his friends at this time, but this year everyone is busy. Suddenly he gets a message from the Evil Santa, inviting him to school.