One False Note
One False Note is the second book in "The 39 Clues" series. It is written by Gordan Korman, and was published by Scholastic on December 2, 2008. Following the events of "The Maze of Bones", the protagonists Amy and Dan Cahill learn about Mozart and travel to Vienna, Austria to search for the second clue in the 39 Clues competition. "One False Note" entered the Children's Books New York Times Best Seller list at number one on December 21, 2008 and stayed on the list for children's chapter books for 12 weeks.
Doublecross (series)
The 39 Clues: Doublecross is the fourth series in the 39 Clues series of books. It follows the story of the Cahills as they suffer from infighting. In the first book, Mission Titanic, Ian Kabra has become the new leader of the Cahills. Dan and Amy decided to take a break from the Cahills after nearly dying from combating Pierce and his thugs. Although Ian believe that he is much more fit to rule the Cahills that Amy and Dan, it seems that the Cahills do not fully recognize Ian as the leader. Ian has suspicions that many Cahills are plotting a coup. When this coup is realized, Ian Kabra and Cara Pierce are expelled from the Cahill home in Attleboro, Massachusetts. The leader of the coup is the Outcast, and he plans to replicate history's worst disasters in order to test Cahill leadership. The Cahills are expected to prevent the disasters in order to prove that they are worthy. Throughout the series, the Cahills make many shocking discoveries, discovering that Grace was actually ruthless and cruel, and that the Outcast is Nathaniel Hartford, the husband of Grace whom Grace wanted dead. There are four books in the series: