Katherine "Kat" Decker is a seventeen-year-old girl who dreams of becoming a singer-songwriter. However, after her father, Jason, died, she is left in the care of her cruel, snobbish stepmother, Deirdre, and her two equally cruel and snobby stepsisters, Joy and Grace. They work Kat to the bone as a servant, have full control of her inheritance, and take a big percentage of her wages from work (theoretically to pay for her disabled dog's food and care). Kat's goal is to make enough money to move out of her home and pursue her dreams.
Kat works at "Santa Land", a Christmas entertainment park, as a singer and song-writer along with her best friend, Isla, under the eye of their strict boss, Mr. Mujiza. There they meet a teenage boy who is the new Santa. Unknown to them he is really Dominic "Nick" Wintergarden, son of billionaire, Terrence Wintergarden. After Nick sees Kat perform, he is smitten by her. Later he confides that he manages a few bands but has never told his dad about this.
Deirdre wants to go to a charity event Terrence is hosting, but she doesn't have a way to get in. Then through Grace's mumbling, she realises that Terrence was Kat's late father's best friend. They devise a plan to gain invitations for the charity event as Deirdre being the widow of the late Jason Decker. However, a letter from Terrence requests the presence of Deirdre and Katherine Decker, so Joy will be impersonating Kat to make the scam work in their favor while leaving the real Kat at home.
As Christmas Eve nears, Nick and Kat become attracted to one another. Nick then gives Kat an invitation to the Wintergarden charity event, much to Kat's surprise and bewilderment, and she accepts the invitation. The next day, Nick reveals his true identity to Kat, and tries to encourage her to do the same but she doesn't. Kat, while reluctant to go to the event with Dominic, is persuaded by Isla to do so when she gives her a green dress they saw at an expensive boutique store which Isla has handsewn herself.
The next morning, however, her stepfamily steal the dress and Deirdre burns her invitation to prevent her from going. Kat calls Isla about what her stepfamily did, and is informed that Dominic has invited her to come over to his home and hear her sing with his friend. When she does come over, Kat gets an unfriendly reception from Nick's friends, especially his girlfriend, Skyler, which eventually causes her to leave.
On the day of the charity event, Kat catches her stepfamily in possession of her late father's snow globe. During the altercation to get it back, the snow globe breaks and kat is left heartbroken. While sobbing, Kat's dog, Bruno, stumbles upon the invitation letter from Terrence. Realizing their intention of using her identity, she becomes determined to stop them. To help Kat get into the event, Isla uses her position as a dressmaker for the event's main show to help her pass as one of the elf performers. But before Kat can get to Terrence, she is forced to go on stage and perform, which she does poorly. In the middle of the performance, both Deirdea and Nick see Kat and both try to get to her. Skyler tries to get together with Nick, but Nick breaks up with her.
Kat unintentionally knocks out one of the performers in the show, and is forced to be the Snow Queen for the next part. Kat sings. Nick and Kat finally find each other. Nick apologises for hurting her and Kat apologises for ruining the show. Before leaving, Nick advises Kat to follow her dreams for her father's sake. Kat then gives a wonderful performance to the audience with a new song she wrote.
After the show, Nick introduces Kat to Terrence. After hearing Kat's problems with her stepfamily and her financial insecurities, Terrence offers to help her as a last wish to his late friend, then he orders Deirdre, Joy and Grace to leave. Nick and Kat finally get to happily dance together.
