39 Clues: The Maze of Bones, by Rick Riordan

This was fantastic!!!!!!! I am literally aching to read the rest of the series. I don't know why it took me so long, I sent this to my nephews about 2 years ago, but didn't read one myself until yesterday!
The Cahill family, whose members have included just about every important historical figure, is divided into 4 branches, who are racing each other around the world to solve a set of 39 clues left by the family matriarch in her will. Excellent puzzles, history, setting- this one was Paris, and made me want to crawl around the Catacombs and climb Mont Martre on a stormy night- great (if briefly introduced) characters- this was a wonderful start to what I hope is a great series!