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The Secret Warning

Age rating, content warnings & parent guide

Leslie McFarlane · 1938

Is The Secret Warning appropriate for your child? See the reviewed age guidance, content cautions, positive themes, and supporting evidence below.

Explore the age guidance, content cautions, positive qualities, and supporting notes for The Secret Warning by Leslie McFarlane. This book is content notes include Frightening scenes, Violence, Products & advertising; positive qualities include Courage & resilience, Creativity & curiosity.

Book 17 · The Hardy BoysSource checked

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10-second decision

Is this likely to fit your family?

Age guidanceNot listed
Strongest cautionsFrightening scenes 2/5 · Violence 2/5 · Products & advertising 1/5
Strongest positivesCourage & resilience 3/5 · Creativity & curiosity 3/5
Series positionBook 17 · The Hardy Boys
Recommendation3/5

Courage & resilience; strongest caution: frightening scenes.

This is the quick scan. Open the evidence and methodology below for the basis behind each rating.

Quick context

What parents should know

Courage & resilience; strongest caution: frightening scenes.

Readiness snapshotMain watch-out: Frightening scenes 2/5
Recommendation 3/5

Editorial rating

How this review was built

Dickens & Rumi editorial
Source checkedPublication method
11Scored categories
11Evidence notes
0Explicit 0/5 checks
Oct 30, 2026Last updated

Dickens & Rumi describes what is present; families decide what matters to them. Community reactions are kept separate from official content ratings.

Review depth11 scored categories11 evidence notes
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At a glance

Recommended ageNot listed

Strongest cautions

  • Frightening scenes2/5
  • Violence2/5
  • Products & advertising1/5

Strongest positives

  • Courage & resilience3/5
  • Creativity & curiosity3/5
  • Good role models3/5

Reading order

Series progression

All known volumes are shown. Reviewed books include age guidance and cautions; books still being reviewed are clearly marked.

Next volumeBook 18 · The Flickering Torch MysteryStrongest cautions: Frightening scenes 2/5 · Violence 2/5Open next review →
  1. Book 1 · The tower treasureAges 10+
    Death of a character2/5Frightening scenes2/5Violence2/5
    Starting point
  2. Book 2 · The House on the CliffAges 9+
    Frightening scenes3/5Violence3/5Alcohol or drugs2/5Death of a character1/5Strong language1/5
    Gets more intense
  3. Book 4 · The Missing Chums
    Frightening scenes3/5Death of a character2/5Violence2/5Products & advertising1/5Romance1/5Strong language1/5
    About the same
  4. Book 5 · Hunting for Hidden Gold
    Frightening scenes3/5Violence3/5Death of a character1/5Graphic injury1/5Products & advertising1/5Strong language1/5
    About the same
  5. Book 6 · The Shore Road Mystery
    Frightening scenes2/5Violence2/5Products & advertising1/5Strong language1/5
    Gets gentler
  6. Book 7 · The secret of the caves
    Frightening scenes3/5Violence3/5Products & advertising1/5Romance1/5Strong language1/5
    Gets more intense
  7. Book 8 · The Mystery of Cabin Island
    Frightening scenes2/5Violence2/5Death of a character1/5Products & advertising1/5Romance1/5Strong language1/5
    About the same
  8. Book 9 · The Great Airport Mystery
    Frightening scenes2/5Violence2/5Alcohol or drugs1/5Death of a character1/5Products & advertising1/5Strong language1/5
    About the same
  9. Book 10 · What Happened at Midnight
    Frightening scenes3/5Violence2/5Strong language1/5
    Gets gentler
  10. Book 11 · While the Clock Ticked
    Frightening scenes2/5Violence2/5Alcohol or drugs1/5Death of a character1/5Products & advertising1/5Romance1/5Strong language1/5
    Gets more intense
  11. Book 12 · Footprints Under the Window
    Frightening scenes3/5Violence2/5Alcohol or drugs1/5Strong language1/5
    Gets gentler
  12. Book 13 · The Mark on the Door
    Frightening scenes3/5Violence2/5Alcohol or drugs1/5Death of a character1/5Products & advertising1/5Romance1/5Strong language1/5
    Gets more intense
  13. Book 14 · The hidden harbor mystery
    Strong language4/5Frightening scenes3/5Violence3/5Graphic injury1/5Products & advertising1/5
    Gets more intense
  14. Book 15 · The Sinister SignpostAges 9+
    Frightening scenes3/5Violence2/5Death of a character1/5Products & advertising1/5Strong language1/5
    Gets gentler
  15. Book 16 · A Figure in Hiding
    Frightening scenes4/5Violence3/5Death of a character1/5Graphic injury1/5Products & advertising1/5Religious themes1/5Strong language1/5
    Gets more intense
  16. Book 17 · The Secret Warning
    Frightening scenes2/5Violence2/5Products & advertising1/5Romance1/5Strong language1/5
    Gets gentler
  17. Book 18 · The Flickering Torch Mystery
    Frightening scenes2/5Violence2/5Romance1/5Strong language1/5
    About the same
  18. Book 19 · The Melted Coins
    Frightening scenes3/5Violence2/5Alcohol or drugs1/5Products & advertising1/5Romance1/5Strong language1/5
    Gets more intense
  19. Book 20 · The Short-Wave Mystery
    Frightening scenes2/5Violence2/5Death of a character1/5Products & advertising1/5Strong language1/5
    Gets gentler
  20. Book 21 · The Secret Panel
    Frightening scenes3/5Violence2/5Alcohol or drugs1/5Death of a character1/5Products & advertising1/5Romance1/5Strong language1/5
    Gets more intense
  21. Book 22 · The Phantom Freighter
    Frightening scenes3/5Alcohol or drugs2/5Violence2/5Strong language1/5
    Gets gentler

Keep going

What should you do next?

One review should lead naturally to the next useful choice.

What’s in it?

Products & advertising1/5
Why this rating?

Part of a long-standing commercial series but does not promote specific products.

Strong language1/5
Why this rating?

Very mild, period-appropriate language.

Romance1/5
Why this rating?

Minimal to no focus on romance.

Frightening scenes2/5
Why this rating?

Includes suspenseful moments and threatening situations characteristic of the Hardy Boys series.

Violence2/5
Why this rating?

Contains typical mild scuffles and physical confrontations common in vintage juvenile mystery fiction.

What’s good in it?

Courage & resilience3/5
Why this rating?

Central theme of the brothers facing danger with bravery.

Creativity & curiosity3/5
Why this rating?

Inspires curiosity and deductive reasoning.

Educational value1/5
Why this rating?

Encourages critical thinking and reading.

Kindness & empathy2/5
Why this rating?

Characters exhibit helpfulness and cooperation.

Positive messages3/5
Why this rating?

Promotes honesty, courage, and working together to solve problems.

Good role models3/5
Why this rating?

The Hardy brothers are proactive, intelligent, and helpful youths.

Family discussion

Talk about it

Conversation starters based on this title’s published content notes.

  1. What did courage look like in this story? Was being brave always the same as being fearless?
  2. Which moment felt most tense or frightening? What helped the characters handle fear?
  3. Which choice in The Secret Warning would you have made differently, and why?
  4. Who changed the most in The Secret Warning, and what caused that change?
Discuss this title with other parents

Community perspective — separate from editorial ratings

What families noticed

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