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.
After seven members of their family are kidnapped by an organization called the Vespers, Dan and Amy Cahill must race against time to track down an ancient map to pay as ransom to bring the hostages home.
Unable to return to their normal lives despite the end of the Clue hunt, new Madrigal leaders Amy and Dan anxiously prepare for a retaliatory strike by the Vespers, who kidnap a number of Cahill family members and demand that Amy and Dan steal a famous painting.
Fourteen-year-old Amy Cahill and her younger brother Dan thought they could return to their regular lives when they found the 39 clues. But the Vespers, powerful enemies, will stop at nothing to get the clues. And with the Vespers rising, the world is in jeopardy.
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.