This analysis was generated by AI from publicly available reader reviews, literary criticism, and book discussions. It has not been verified by a BookLens community reviewer and may contain errors. Be the first to verify →
Content snapshot
Flag an inaccuracy →What's in this book, at a glance — five things readers want to know before they start.
Violence
Very heavy
Graphic serial killer violence; body parts as trophies; detailed scenes of abduction and torture
Language
Some
Moderate profanity in crime thriller context
Sexual Content
Barely any
References to past abuse; minimal sexual content
Substance Use
Barely any
Minimal substance use
Emotional Intensity
Very heavy
Intensely disturbing serial killer psychology; traumatic backstories; graphic crime content throughout
What this book is about
Detective Sam Porter has hunted the 4MK killer for years — a man who mails his victims' ear, eye, and tongue before killing them. When 4MK dies in a hit-and-run with a fresh victim's box in hand, Porter must decode his disturbing diary to find the girl before time runs out. A graphic and relentless debut thriller.
Notes for sensitive readers
Reader-flagged moments and themes that may affect your experience.
Graphic serial killer violence
Body part trophies
Abduction and murder of women
Disturbing psychological content
Reader Verification
Be the first to verify
this rating
Have you read The fourth monkey? Submit a community rating to confirm or correct the AI estimate. Your review helps other readers make an informed choice.
Rate this book →Free · ~5 minutes · No account required
Similar reads
More Mystery books from the catalog.
Think this AI estimate is off?
Flag an inaccuracy →Where to Buy
Affiliate links — BookLens earns a small commission at no extra cost to you.