It's Christmas and the Five are together again. But alas! They cannot escape the new tutor Uncle Quentin has appointed for them. The children don't like him very much and nor does Timmy. Soon the Five discover that Uncle Quentin's important scientific papers have gone missing. And they see their tutor meeting two men that he later denies. The Five decide to take matters into their own hands and put an end to these absurd happenings themselves. How will they do it?