The 39 Clues: Doublecross Series is the 4th story arc in the 39 Clues Franchise, sequel to Unstoppable Series. It features 4 exciting adventure books for young adult readers, published between 2015 and 2016. The books are written by four different authors and among them, only Jude Watson has previously written books in the series. For the other three authors (C. Alexander London, Jenny Goebel, and Sarwat Chadda), their books are their first in the 39 Clues series.
The Outcast is a banished member of the Cahill family. No one in the family ever mentions him again. However, he has always watched the family and decides to make some actions to realize his revenge. He challenges the Cahills to stop him from recreating four of the most catastrophic disasters in history. To prevent deaths of thousands of innocent people, Amy and Dan Cahill will have to race around the world and figure out what the Outcast’s plans and his targets are. More than that, what the Outcast actually wants behind all the terror will shock the entire Cahill family.
Summary of the Series
The Outcast was banished from the Cahill family, never mentioned again. For years, he’s been watching, recruiting, waiting for the chance for revenge. And now he strikes, with a diabolical plan. The Outcast recreates four of history’s most infamous disasters, and gives the Cahill kids just days to stop them. There are innocent lives on the line, but what might be worst of all is the doublecross that the Cahill kids don’t see coming…