A thick book, touched with delicate fingers and enthusiastically closed: a great achievement in both the literal and figurative sense. Mysterious letters arrive in the mailbox of 15-year-old Sofie Amundsen in Oslo. What do these questions mean: "Who are you?", "What is a human?", and "Where does the world come from?". Sofie is puzzled. The letters become more detailed and lead her into the adventurous and mysterious world of thought of great philosophers. Her unknown correspondent tells Sofie the history of Europe, antiquity, the Middle Ages, and the Renaissance, and then the story takes an incredible turn.