Amy and Dan are shocked to learn that Outcast, a violent renegade who's threatening the lives of innocent people, may be a Cahill family member who's determined to exact revenge.
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!
The Outcast recreates the conditions for the Titanic disaster and gives Dan and Amy Cahill just days to stop the shipwreck from taking place.
Thirteen-year-old Dan Cahill and his 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 travel from the hottest to the coldest regions of the world in order to stop someone from using their own power against them.
Chronicles the first Vesper attack on Jan van Eyck's altarpiece at Ghent in the 1600s, then jumps to WWII and young Grace Cahill's desperate bid to save the masterwork from the Nazis.
After delivering the last ransom, Amy and Dan discover that Vesper One has a terrifying plot and they race against time to stop him from harming millions of innocent people.
Targeted by Interpol after a series of spectacular heists, a reluctant Amy and Dan are ordered by Vesper One to steal the world's largest diamond, a demand that is challenged by their efforts to rescue the Cahill hostages and stop a Vesper mole.
When the Vespers continue their abductions and cross a line by kidnapping Atticus, an 11-year-old non-Cahill civilian and Dan's only friend, Dan and Amy confront their biggest challenge ever in order to keep Atticus alive.