Vespers Rising (The 39 Clues, Book 11)

Vespers Rising - Rick Riordan, Peter Lerangis, Gordon Korman, Jude Watson After 10 books in the '39 Clues' series, the 11th book finally presents the back story -- and is a collaborative piece between 4 different authors, who had previously written one (or two) books each in the series . And this is the best story, so far....