Sign of Four
Arthur Conan Doyle
Sign of Four
Age Rating, Reading Level & Content Guide
by Arthur Conan Doyle
The text is written at a 4th grade reading level, the subject matter is intended for middle graders (ages 9–12), and the content has moderate intensity with some emotionally heavy themes.
We may earn a commission from these links. Bookshop.org supports independent bookstores with every purchase.
About This Book
The clock is ticking as Mary Morstan clutches a mysterious note in her trembling hand. Sherlock Holmes and Dr. Watson burst into the room, ready to chase secrets that stretch from shadowy streets to faraway lands. But just as they’re about to uncover the truth, a chilling danger closes in—what will happen next?
Quick Assessment
Set in 1888, this middle-grade mystery follows Mary Morstan as she enlists Sherlock Holmes and Dr. Watson to solve the puzzling disappearance of her father and a series of strange gifts. The story involves themes of betrayal, murder, and addiction, and includes some intense moments with references to substance use, injury, and death. Suitable for readers aged 9-12 who can handle mature themes within a classic detective adventure.
Why we rated Sign of Four 9ME
Sign of Four is written at a Level 4-5 reading level across 152 pages. Strong independent readers around grade 5.5 can typically handle this book on their own; with parent or teacher support, Sign of Four works for readers up to grade 6.5.
We rate Sign of Four as 9ME ("Moderate — Emotional") because the content sits in the "Moderate" range — moderate conflict that may involve loss, scary scenes, or interpersonal stakes. The strongest signals come from emotional weight, physical peril, social complexity — these are the dimensions parents should evaluate against their reader's tolerance.
Specific content flags noted by reviewers: Addiction, Alcohol Abuse, Drug Use, Injury, Restraint, Death of Parent, Death of Family Member, Natural Bodies of Water.
Thematically, Sign of Four explores mystery, adventure, friendship, and family — 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.
- ✓ Kids drawn to stories about mystery, adventure, friendship.
Maybe not for
- ! Readers who get easily upset by emotional or moderately dark scenes — the conflict here is real, not just background flavor.
- ! Children currently coping with grief — the themes may hit close to home.
For Parents
Content Intensity
9ME — Moderate — EmotionalReal stakes and emotional weight. May include sustained danger, loss, or bullying.
Content Flags
Was our "Moderate" content intensity rating accurate for this book?
Reading Insights
Hook Factor
3/10A steady, thoughtful read that rewards patient readers.
Discussion Potential
3/10A lighter read — great for independent enjoyment.
Book DNA
Multi-dimensional content fingerprint
Similar Books
Based on content and theme analysis
Sir Arthur Conan Doyle's the Adventures of Sherlock Holmes, Book Four
A. Conan Doyle
Sir Arthur Conan Doyle's the Adventures of Sherlock Holmes, Book Four
A. Conan Doyle
The Adventure of the Speckled Band
Arthur Conan Doyle
The Adventure of the Speckled Band
Arthur Conan Doyle
The Speckled Band
Arthur Conan Doyle
The Speckled Band
Arthur Conan Doyle
Study in Scarlet
Arthur Conan Doyle
Study in Scarlet
Arthur Conan Doyle
Sir Arthur Conan Doyle's the Adventures of Sherlock Holmes
Arthur Conan Doyle
Sir Arthur Conan Doyle's the Adventures of Sherlock Holmes
Arthur Conan Doyle
Study in Scarlet
Arthur Conan Doyle
Study in Scarlet
Arthur Conan Doyle
Details
Book Length
- ISBN
- 9780198355359
- Pages
- 152
- Publisher
- Oxford University Press, USA
- Published
- 2015
- Type
- Fiction