One belief has sustained fourteen-year-old Amy Cahill and her younger brother Dan on their hunt for the 39 Clues: They are the good guys. But then a shocking discovery about their parents shatters everything Amy and Dan think they know, dividing thetwo siblings for the first time ever. When Dan disappears in the country of more than a billion people, Amy has to make a terrible choice — find the next Clue... or find her brother.