The Maze of Bones launches The 39 Clues, the multimedia adventure series created and plotted by Rick Riordan, who wrote this opening book. When wealthy matriarch Grace Cahill dies, her will offers each relative a choice: take a million dollars and walk away, or forfeit the money to join a worldwide treasure hunt for 39 hidden clues that will reveal the source of the Cahill family's vast power. Orphaned siblings Amy and Dan Cahill, raised by their dismissive Aunt Beatrice and devoted to their late grandmother Grace, accept the challenge. With their au pair Nellie Gomez and Grace's Egyptian Mau cat, Saladin, they fly to Paris to chase a first clue tied to their ancestor Benjamin Franklin, decoding his Poor Richard's Almanack and tracking a sinister "maze of bones." Standing in their way are scheming relatives from rival Cahill branches: the wealthy Kabra siblings Ian and Natalie, the athletic Holt family, the celebrity Jonah Wizard, the cunning Alistair Oh, and Russian ex-spy Irina Spasky. The book establishes that historical greats from Napoleon to Houdini all descend from the Cahills, and that the family's lost secret could change the world. A fast, puzzle-driven mystery aimed at middle-grade readers, it interlaced its plot with six collectible game cards and an online game where readers competed alongside the story, debuting at number one on the New York Times bestseller list.