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The Mystery of the Deadly Double

Dennis Lynds · 1978

Explore the age guidance, content cautions, positive qualities, and supporting notes for The Mystery of the Deadly Double by Dennis Lynds. This book is content notes include Frightening scenes, Violence, Strong language; positive qualities include Courage & resilience, Good role models.

Book 28 · The Three InvestigatorsSource 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 · Strong language 1/5
Strongest positivesCourage & resilience 4/5 · Good role models 4/5
Series positionBook 28 · The Three Investigators
Recommendation3.5/5

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 3.5/5

Editorial rating

How this review was built

Dickens & Rumi editorial
Source checkedPublication method
10Scored categories
10Evidence notes
0Explicit 0/5 checks
Nov 6, 2026Last updated

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

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At a glance

Recommended ageNot listed

Strongest cautions

  • Frightening scenes2/5
  • Violence2/5
  • Strong language1/5

Strongest positives

  • Courage & resilience4/5
  • Good role models4/5
  • Creativity & curiosity3/5

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 30 · The Secret of Shark ReefStrongest cautions: Frightening scenes 2/5 · Violence 2/5Open next review →
  1. Book 12 · The Mystery of the Laughing Shadow
    Frightening scenes3/5Violence2/5Strong language1/5
    Starting point
  2. Book 18 · The Mystery of the Shrinking House
    Frightening scenes3/5Violence2/5Death of a character1/5Strong language1/5
    About the same
  3. Book 19 · The Secret of Phantom Lake
    Frightening scenes3/5Violence2/5Strong language1/5
    About the same
  4. Book 22 · The Mystery of the Dead Man's Riddle
    Death of a character1/5Frightening scenes1/5Violence1/5
    Gets gentler
  5. Book 25 · The Mystery of the Dancing Devil
    Frightening scenes2/5Strong language1/5Violence1/5
    About the same
  6. Book 26 · The Mystery of the Headless Horse
    Violence2/5Death of a character1/5Frightening scenes1/5Strong language1/5
    About the same
  7. Book 28 · The Mystery of the Deadly Double
    Frightening scenes2/5Violence2/5Strong language1/5
    About the same
  8. Book 30 · The Secret of Shark Reef
    Frightening scenes2/5Violence2/5Strong language1/5
    About the same
  9. Book 33 · The Mystery of the Purple Pirate
    Frightening scenes2/5Violence2/5Products & advertising1/5Strong language1/5
    About the same
  10. Book 38 · The Mystery of the Smashing Glass
    Frightening scenes1/5Violence1/5
    Gets gentler
  11. Book 42 · The Mystery of Wreckers' Rock
    Frightening scenes2/5Violence1/5
    About the same

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What’s in it?

Strong language1/5
Why this rating?

Language appears generally youth-appropriate, with at most mild exclamations or insults.

Frightening scenes2/5
Why this rating?

Suspicious situations, threats, and tense investigative moments may be mildly frightening, without strong horror imagery.

Violence2/5
Why this rating?

Mild threats and occasional physical conflict fit a teen detective adventure; violence is not described as graphic or especially intense.

What’s good in it?

Courage & resilience4/5
Why this rating?

The protagonists face intimidating situations to investigate mysteries and help others, showing substantial bravery.

Creativity & curiosity3/5
Why this rating?

Clues, deduction, and unconventional investigation invite imaginative thinking and creative problem-solving.

Diverse representation1/5
Why this rating?

The available information does not indicate broad representation; conclusions are limited without character or plot passages.

Educational value2/5
Why this rating?

It may encourage deduction and problem-solving, but teaching factual knowledge does not appear to be its main purpose.

Kindness & empathy3/5
Why this rating?

Friendship, teamwork, and helping others appear to be recurring positive behaviors.

Positive messages3/5
Why this rating?

The story appears to value careful reasoning, persistence, cooperation, and solving problems rather than relying on guesses.

Good role models4/5
Why this rating?

The young investigators are described as supportive, persistent, and honest, though their risk-taking may not always be ideal.

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 Mystery of the Deadly Double would you have made differently, and why?
  4. Who changed the most in The Mystery of the Deadly Double, and what caused that change?
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Community perspective — separate from editorial ratings

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Community ratings and written reactions are a separate layer. They do not automatically change Dickens & Rumi’s official age guidance or content scores.

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