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 enough 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...

"CALLING ALL CAHILLS! Announcing a 39 Clues Superspecial adventure -- the gang is back and called to investigate one of their own: Sinead Starling."-- Provided by publisher

Thirteen-year-old Dan Cahill and his older sister Amy race against time to find an ancient map that has not been seen for half a century and use it to redeem their family members who have been kidnapped by a sinister organization called the Vespers.

Dan Cahill and his sister Amy travel from the hottest to the coldest regions of the world in order to stop someone from using their own power against them.

Thirteen-year-old Dan Cahill and his older sister, Amy, are the latest guardians of the Clues -- thirty-nine ingredients in a serum that transforms whomever takes it into the most powerful person on earth. They think they've done everything right, but a tiny mistake leads to catastrophe. The serum is missing and Dan and Amy have to get it back and stop who stole it ... before it's game over.

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.

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.