The Maze of Bones

The Maze of Bones is the first novel of The 39 Clues series, written by Rick Riordan and published on 9 September 2008 by Scholastic. It introduces Amy and Dan Cahill, two orphans who discover, when their grandmother Grace dies, that they are part of the powerful Cahill family.

The will offers each of the heirs a choice between a million dollars and a place in the contest for the thirty-nine clues, which are supposed to lead to the source of the family's influence. Amy and Dan take the contest, and this first volume follows them to Paris and to a set of family secrets, with their relatives competing for the same prize and not all of them playing by the rules.

The series was designed as a multi-author sequence with a website and collectible cards alongside the books, and Riordan established that structure here. It was followed by further volumes by other writers, each following the same contest from a different part of the family, which is why the first book does so much setting up.