authordanbrown announces his new book “The Secret of Secrets” is out everywhere September 9th! “‘The Secret of Secrets’ is by far the most intricately plotted and ambitious book that I have ever written, and I also happen to think it’s the most fun.” The new thriller from the bestselling author of “The Da Vinci Code” will reunite fans with Harvard symbologist Robert Langdon in love and on the run. #thesecretofsecrets