Could Amy and Dan's biggest enemy be. a friend? Book 6 challenges everything you thought you knew about the Clues race. A hint from their parents' past puts Amy and Dan on the trail of secrets their grandmother Grace would NEVER have wanted them to know. Awful memories begin to crowd in on Amy, just as her enemies circle closer. How far would she go to protect Dan? How much of a Cahill is she prepared to be? Perhaps Grace was right - some secrets are better left buried.