As a trainee of Santa Company, Noel White prepares for her test to become an official Tonttu, her assignment being 'To find the most important thing for a Santa Claus.' The deadline nears with an answer yet to be found, when a single letter from a child arrives late at the company. As the letter is about to be handled as a defect, Noel and friends set out on an adventure for the present - but will Noel find the answer to her assignment? Set a year after the events of the novel.