What is the resolution in the 39 clues maze of bones?

In "The 39 Clues: Maze of Bones," the resolution involves Amy and Dan Cahill locating the final clue in Benjamin Franklin's grave beneath Christ Church in Philadelphia. They discover the clue, a tuning fork, and realize it represents the musical note "A" for Amy, who is a musical prodigy. This clue leads them to the next adventure in the series.