Colorado Parks & Wildlife Research Library

One belief has sustained fourteen-year-old Amy Cahill and her younger brother, Dan, on their hunt for the 39 Clues: They are the good guys. But then a shocking discovery about their parents shatters everything Amy and Dan think they know, dividing the two siblings for the first time ever. When Dan disappears in a country of more than a billion people, Amy has to make a terrible choice - find the next Clue . . . or find her younger brother.

Throughout the hunt for the 39 Clues, Amy and Dan Cahill have uncovered history's greatest mysteries and their family's deadliest secrets. But are they ready to face the truth about the Cahills and the key to their unmatched power? After a whirlwind race that's taken them across five continents, Amy and Dan face the most the difficult challenge yet -- a task no Cahill dared to imagine. When faced with a choice that could change the future of the world,...

Chris and Carrie have been betrayed. Maddison has discovered the dark secret in her father's past. A cold case is suddenly hot--and has changed from "missing" to " murder." As a crime wave hits Archer's Grove and authorities struggle to catch the culprits, Chris, Carrie, and Maddison turn to the Kingsolvers' Aunt Elsie for answers. Can the notebooks she left behind illuminate this tangled web of lies, betrayals, and broken promises? Will the truth...

Amy and Dan cross the oceans on the trail of a famous aviator, but they find more than they're looking for. Their enemies are becoming more vicious, and the truths they discover more crushing than ever.

What would happen if you discovered that your family was one of the most powerful in human history? What if you were told that the source of the family's power was hidden around the world, in the form of 39 clues? What if you were given a choice - take a million dollars and walk away ... or get the first clue? If you're Amy and Dan Cahill, you take the clue - and begin a very dangerous race.

A mysterious telegram sends Amy and Dan Cahill off to Russia, where they search for a treasure stolen by the Nazis, the truth about the end of the Romanov dynasty, and information about the death of their parents.

Thirteen-year-old Dan Cahill and his older sister, Amy, are running out of time. An exiled Cahill known as the Outcast has already recreated of history's worst disasters, and he's saved the worst for last. If Dan and Amy can't find and stop Outcast fast, he will initiate a full-scale nuclear meltdow.

While working at Bletchley Park transcribing decrypted signals from the German Army as it marches into Leningrad, Honey Deschamps begins to receive mysterious packages from Russia containing small pieces of amber that suggest a coded message.

"The Vespers have crossed a line. Amy and Dan were devastated when the Vespers kidnapped seven Cahills around the world, holding them hostage until Amy and Dan delivered an impossible ransom. But at least the hostages were Cahills - members of the world's most powerful family, trained to face all odds. Now the Vespers have gone too far. They've kidnapped Atticus, an innocent 11 year old boy and Dan's only friend. Now Dan and Amy are in the struggle...

Charlie, Anna, and Emily must overcome their differences and work together to solve various puzzles leading to the secret treasure a famous female explorer left in Idlewood Manor before the adults do.