Mission Hindenburg [39 clues. Doublecross Volume: bk. 2]by London, C. Alexander 

BTSB Prebound(Scholastic, 2015)

BTSB #: 584776 Available

Dewey: FAges: 9-12   
AR: 5.5 MG Lexile: 810

Genres: Mystery Fiction Adventure Fiction

Subjects: Adventure fiction Aircraft accidents - Fiction Siblings - Fiction

Summary: The Cahills are the world's most powerful family, but their strength is being tested. A sinister man calling himself The Outcast has targeted the family and sent them an impossible test. He's recreating four of history's worst disasters and challenging the young Cahills to find and stop the tragedies before it's too late. Now, with one disaster behind them, siblings Dan and Amy Cahill and their friends have just days to discover what the Outcast's next move will be.

Mission hurricane [39 clues. Doublecross Volume: bk. 3]by Goebel, Jenny 

BTSB Prebound(Scholastic, 2016)

BTSB #: 382968 Available

Dewey: FAges: 9-12   
AR: 5.9 MG RC: 5.4 3-5 Lexile: 830

Genres: Mystery Fiction Adventure Fiction

Subjects: Adventure fiction Mystery fiction

Summary: Who is the Outcast and why is he threatening the lives of innocent people? A shocking secret is revealed that will send Amy and Dan--and the world--reeling.