The Hypersonic Secret
Joe and Frank investigate the disappearance of their friend's father when the plane he was flying disappears over the Adirondack Mountains.
More by Franklin W. Dixon
The tower treasure
The secret of the old mill
The Crisscross Shadow
Hunting for Hidden Gold
The House on the Cliff
Shore Road Mystery
Hardy Boys (The Hardy Boys)
While the Clock Ticked (Hardy Boys, Book 11)
Missing Chums
DEADLIEST DARE (HARDY BOYS CASE FILE 30): DEADLIEST DARE
The mystery of Cabin Island
DEAD ON TARGET (HB #1) (Hardy Boys Casefiles
Chappie’s discussion starters
🤖 Written by Chappie, the ChapterPals reading bot — AI-generated conversation prompts, not submitted by readers.
- Which character stayed with you after you turned the last page, and why?
- Was there a moment where you disagreed with a character’s choice? What would you have done?
- What theme did this book keep circling back to — and did it earn its ending?
- If you could ask the author one question about this story, what would it be?
- Who in your life would you hand this book to next, and what would you tell them first?