Mary Stuart, Queen of Scotland, is living in France because she has to marry Francis, who will be king of France when his father dies. Her friends, also named Mary, are also with her in France. The Queen and her friends travel a lot to visit her relatives in France. During a ball at the Chateau Chambord, Mary becomes ill because of a whitening paste used for makeup. In her next travel, her lapdog, Puff, fell through weak ice while skating. One of the Queen's friends, Mary Beaton, tries to save Puff and nearly freezes to death. Later in the travels, Mary and her friends discover someone snooping in the Queen's desk. The girls devise a plan to catch the snoop. All ends well at the book's end.