The year is 1850 and the soon-to-be 13-year-old Karen has to start as a maid at the nearby manor house. But turning 13 also means she can no longer see her best friend and protector of the manor, the goblin Rumle. Therefore, Rumle and Karen are tempted to create a magical Christmas heart together, so that they will be friends forever anyway. But suddenly all kinds of mysterious things and accidents start happening at the manor... December will be a magical adventure and a great trial for Karen, where she must save Rumle from the evil Lars Ravn, try to change the Christmas heart so that the manor can return to where it was before the Christmas heart was created and at the same time time to take care of her new jobs. But Karen also has to realize that she is the one who has to let go of Rumle before everything can be okay again.