The third book in the detective series with riddles and puzzles, sold in France with a total circulation of more than 30 thousand copies. Olivier, Thomas and Amanda conduct a video blog about historical secrets and their own investigations. One day they receive a mysterious letter from a subscriber: a boy named Noah begs for help... What does the mysterious manuscript that Noah’s father, the author of treasure-hunting quests, hide so carefully? And why is Aunt Noah so desperate to get her hands on this book? For answers, the heroes will go to Paris - to a huge amusement park! Features of the book - French Amazon bestseller in the children's detective genre - The series was sold in France with a total circulation of more than 30 thousand copies in the first year of sales - Introduces children to the world of detective literature - Fascinating plot and charming characters that will be close and understandable to children Who is this book for? For children from 10 years old. For fans of exciting detective stories. For fans of history and knightly themes. Published in Russian for the first time.