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. In this book, Amy and Dan 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.