Books that make up Doublecross, the fourth series within The 39 Clues. Trending pages Mission Atomic Mission Hurricane Mission Titanic Mission Hindenburg All items (8) # A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Other M Mission Atomic Category:Mission Atomic Mission Hindenburg Category:Mission Hindenburg Mission Hurricane Category:Mission Hurricane Mission Titanic Category:Mission Titanic Categories: Books by series Doublecross Community content is available under CC-BY-SA unless otherwise noted.