39 Clues - One False Note (Book 2) by Gordon Korman

After the loss of their grandmother Grace Cahill, Amy and Dan Cahill, find out they are members of the most influential family in history. But the family is divided and after the reading of Grandma Graces's will and no parent lalive help them, the children are pitted against the rest of their family in a race to rule the world. One False Note has the children, their au pair, Nellie Gomez, and Graces's cat Saladin, tracking through Europe following clues left by their ancestors Wolfgang Amadeus Mozart and Ben Franklin. The pair continue to encounter bomb blasts, secret passages, hidden clues and evade fellow family members bent on taking the clues they have discovered. Will they make it to the next step in the race to rule or will they lose everything?