The 39 clues. Main series

The race is on to find 39 clues that safeguard a great power, and fourteen-year old Amy Cahill and her younger brother, Dan, are shocked to find themselves in the lead. The search seems to be taking them to Vienna, and they hold a coded piece of Mozart's sheet music that's key to finding the next clue. But tailed by a pack of power-hungry relatives, Amy and Dan can't see if they are sailing toward victory or straight into a deadly trap.

A clue found in Book 3 sends Amy and Dan jetting off to Egypt to find out what's behind the fierce rivalry between the Tomas and Ekaterina branches of the Cahill family. Was a clue stolen from the Tomas branch? Where is it now? And, most important, can Amy and Dan get their hands on it before their rivals do?

Amy and Dan Cahill travel to Australia to figure out what their own parents knew about the object of their quest, but their search brings back terrible memories for Amy and endangers a secret ally.

An escalating race to find the 39 Clues finds Amy and Dan pursuing a Clue guarded by thousands of the world's best-trained soldiers, an effort that separates them in explosively dangerous ways.

After crossing five continents and solving some of history's most perplexing mysteries, Amy and Dan Cahill are nearing the end of their adventure. As the final clue promises to reveal the truth about the Cahill family's awesome power, Amy and Dan must successfully complete a challenge that their ancestors have failed for nearly 500 years.

A guide to the characters and situations in "The 39 Clues" outlines the Cahills' secrets, including hidden facts, strategies, agents, lost founders, secret bases, and scandals, as well as information about all branches of the family.