The blockbuster series continues with a Cahill family member from the past bent on revenge! Who is the Outcast, and why is he threatening the lives of innocent people? Book 3 reveals a shocking secret that will send Amy and Dan - and the world - reeling.

Calling all Cahills! Announcing a 39 Clues Superspecial adventure - the gang is back, and called to investigate one of their own: Sinead Starling.

Never turn your back on the Cahills.... The most powerful family history has ever known returns with a vengeance in The 39 Clues: Doublecross! Confidential until August 2015!

At only seventeen years old, Ian Kabra is head of the Cahills, the most powerful family in the world. He has presidents on speed dial, generals at his beck and call. Ian knows he's an ideal leader and the only man for the job. There's just one small problem: He's already messed up big time. A Cahill from the past calling himself the Outcast has risen to challenge Ian with an impossible test. The Outcast has re-created four of history's greatest disasters and dared Ian to stop him.

The 39 Clues is unstoppable! The bestselling series returns with an adventure spanning four explosive books and a website that places listeners right in the action.

As a member of the most powerful family history has ever known, 13-year-old Dan Cahill has been shot at, kidnapped, and even thrown into a pit with a deadly snake. He’s survived it all due to luck, smarts, and his older sister, Amy, who always sticks by his side. Now Dan and Amy are facing their greatest threat yet, an enemy who has found a way to use the source of the Cahill family power against them.

International best seller David Baldacci pens the stunning conclusion to Cahills vs. Vespers! David Baldacci is the author of 23 books for adults, each of which has become both a national and international best seller.

A surprising twist brings Amy and Dan back to New England for their first mission on U.S. soil since the beginning of the Clue hunt. But being close to home is anything but a comfort. The siblings have learned that there's a mole in the Cahill organization.... And the traitor is one of their closest confidantes. However, this betrayal is overshadowed when Amy and Dan make an even more devastating discovery: the truth about the Vespers' real plan. Burdened with this terrifying information, Amy and Dan are forced to ask an impossible question: Is it more important to save the hostages...or stop the Vespers?

The Cahill family has a secret. For five hundred years, they have guarded the 39 Clues - thirty-nine ingredients in a serum that transforms whomever takes it into the most powerful person on earth. If the serum got into the wrong hands, the disaster would rock the world. So certain Cahills have always made it their mission to keep the serum safe, buried, locked away. Until now. Thirteen-year-old Dan Cahill and his older sister, Amy, are the latest guardians of the Clues. They think they've done everything right, but a tiny mistake leads to catastrophe.

After pulling some spectacular heists, Amy and Dan have become two of Interpol's most wanted criminals. So when Vesper One orders them to steal the world's largest diamond, they know they're facing life in prison...or worse. But with the Cahill hostages still in peril, Amy and Dan have no choice but to launch a mission that leads them to an ancient city full of dangerous secrets. With a Vesper mole sabotaging the Madrigals from inside, Amy and Dan have to fulfill their enemy's request before it's too late. Vesper One has developed a taste for killing Cahills, and Amy and Dan aren't going to wait to see who's next.

The Vespers have ordered Amy and Dan to find a legendary map that belonged to Marco Polo, and the hunt takes them to Eastern Europe where they make a terrifying discovery about one of their supposed “allies.”

Amy and Dan find themselves in a new global race but this time, everything’s different. Those closest to them might be working for the enemy, and Amy and Dan are forced to ask themselves how far they’re willing to go to save the kidnapped Cahills. How much can you risk when there’s no one to trust?

Once Amy and Dan Cahill's choice was simple - take a million dollars or the first of 39 Clues that lead to the source of unimaginable power. Now it's clear that the hunt for Clues is bigger than anything that Amy and Dan could ever have imagined.

On the hunt for the 39 Clues, Amy and Dan Cahill uncovered shocking information about their past - from what happened the night their parents died to the shattering discovery of their family branch. Will Book Nine be the end of Amy and Dan? Or just the end of everything they think they know?

Amy and Dan must steal a Clue guarded by thousands of the world’s best-trained soldiers. With their enemies closing in, the brother and sister are separated. Now how will they stand a chance?