The Hypersonic Secret
Franklin W. Dixon
The Hypersonic Secret
Age Rating, Reading Level & Content Guide
The Hardy Boys #135
by Franklin W. Dixon
The text is written at a 4th grade reading level, the subject matter is intended for middle graders (ages 9–12), and the content is mild with minimal sensitive material.
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About This Book
What would you do if a pilot vanished without a trace during a routine flight? Frank and Joe dive into the mystery, uncovering clues that hint at sabotage and a secret bigger than they imagined. But can they solve the puzzle before the truth slips away?
Themes
Quick Assessment
This middle-grade mystery follows Frank and Joe as they investigate the disappearance of an air taxi pilot, uncovering sabotage and a larger conspiracy involving a wealthy passenger. Suitable for ages 9-12, the book features themes of crime and mystery with suspenseful but age-appropriate content. Parents should note the story includes some tense moments related to disappearance and investigation but no graphic content.
Why we rated The Hypersonic Secret 9LE
The Hypersonic Secret is written at a Level 4-5 reading level across 160 pages. Strong independent readers around grade 5.5 can typically handle this book on their own; with parent or teacher support, The Hypersonic Secret works for readers up to grade 6.5.
We rate The Hypersonic Secret as 9LE ("Light — Emotional") because the content sits in the "Mild" range — mild conflict — the kind a child encounters in normal play and sibling life. Across our four dimensions (emotional, physical, social, thematic) the book reads as evenly mild; no single dimension stands out as a concern.
No specific content flags were raised by community reviewers, which is consistent with the mild intensity score.
Thematically, The Hypersonic Secret explores crime & mystery, adventure, friendship, and juvenile fiction — these threads give the book room to mean different things to different readers.
Good fit for
- ✓ Children in the Ages 9-12 range — the maturity and attention span match the story's pacing.
- ✓ Patient readers who enjoy slower, character-driven stories.
- ✓ Kids drawn to stories about crime & mystery, adventure, friendship.
Maybe not for
- ! Reluctant readers who need a fast hook — the pacing here rewards patience.
For Parents
Content Intensity
9LE — Light — EmotionalLight conflict or tension. Mild peril resolved quickly.
Was our "Mild" content intensity rating accurate for this book?
Reading Insights
Hook Factor
2/10A steady, thoughtful read that rewards patient readers.
Discussion Potential
1/10A lighter read — great for independent enjoyment.
Book DNA
Multi-dimensional content fingerprint
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Details
Book Length
- ISBN
- 9780671505189
- Pages
- 160
- Publisher
- Simon & Schuster/Paula Wiseman Books
- Published
- December 1, 1995
- Type
- Fiction