What Happens When a Serial Killer Dies on Page One — J.D. Barker Shows You.
I Did Not Intend to Finish This Book in One Sitting
Let me be upfront with you.
I picked up The Fourth Monkey on a Tuesday evening with the full intention of reading a chapter or two before bed. Responsible. Measured. Sensible.
That was a mistake.
By midnight I was three hundred pages in, every light in the room blazing, completely unable to explain to myself why I kept reading descriptions that made my stomach turn — and completely unable to stop. There is a very specific type of book that does this to you. The kind that hooks something deep in your brain and refuses to let go no matter how uncomfortable it gets. The Fourth Monkey by J.D. Barker is that book. Completely, unapologetically, brilliantly that book.
If you’ve been looking for where to start with J.D. Barker books in order, this is your answer. Start here. Start tonight. Just don’t make plans for tomorrow.
The book has been described as Se7en meets The Silence of the Lambs — and for once, a publisher’s tagline actually delivers on its promise. This is dark, clever, psychologically layered thriller fiction at its absolute best. And it’s the book that turned J.D. Barker from an impressive horror author into one of the most talked-about thriller writers working today.
Here’s everything you need to know before you read it — and why you absolutely should.
What Is The Fourth Monkey About?
The Setup That Changes Everything From Page One
Most serial killer thrillers open with a murder. The Fourth Monkey opens with the killer’s death.
That single structural decision — starting the story with the Four Monkey Killer stepping in front of a Chicago city bus — is what separates this book from every other entry in its genre. The killer is dead before chapter one ends. And yet the tension never lets up for a single page.
Here’s why.
Detective Sam Porter has spent five years hunting the Four Monkey Killer — known in the media as 4MK — a meticulous, methodical serial killer with a twisted sense of vigilante justice. His victims are always chosen based on the sins of their family members. His calling card: three small white boxes, delivered over several days to someone close to the victim. The first box contains an ear. Hear no evil. The second, an eye. See no evil. The third, a tongue. Speak no evil. And then — the body.
When 4MK dies on that Chicago street, Porter discovers a diary in the dead man’s jacket. A diary that chronicles the killer’s entire life — from a deeply disturbing childhood through the evolution of his murderous methodology. And one more thing: a box. Already in transit. Which means there’s another victim. Still alive. Somewhere. With a clock ticking.
That’s the engine of this book. And it never stops running.
What Makes This Book Genuinely Brilliant
The Dual Narrative Structure
J.D. Barker makes a bold choice with the structure of The Fourth Monkey — alternating between Detective Porter’s present-day race to find the victim and the killer’s diary entries that slowly, methodically reveal his past.
This could have been gimmicky. In lesser hands it would have been. Instead it becomes the book’s greatest strength. The diary entries are deeply unsettling — not because of the violence alone, but because Barker writes the killer’s childhood with such psychological specificity that you find yourself understanding, almost against your will, how a person becomes what 4MK became.
That’s the most disturbing trick in the book. And it works perfectly.
The Pacing Is Merciless
There is no wasted scene in The Fourth Monkey. Every chapter either advances the investigation, deepens the psychological portrait of the killer, or raises the stakes on the missing victim’s survival window. Barker doesn’t let you breathe. He doesn’t want you to.
Readers who’ve explored J.D. Barker books in order consistently say this first entry in the 4MK series is the tightest, most relentlessly paced of the three. The sequels go deeper and broader — but The Fourth Monkey is the purest expression of Barker’s ability to build and sustain tension across 416 pages without losing a single thread.
The Twist at the End
This review will not spoil it. What it will say is this: the final twist is the kind that recontextualizes everything that came before it. Not in a cheap, narrative-cheating way. In the way that makes you flip back through the book and realize the clues were always there — you just didn’t see them.
One reviewer called it “a cracker.” That’s an understatement.
Who Is This Book For?
The Fourth Monkey sits in a very specific zone of thriller fiction. It’s dark. Genuinely dark. There are scenes involving violence and psychological horror that are not for sensitive readers. Barker describes everything with a vividness that is simultaneously impressive and deeply uncomfortable — exactly as intended.
If you love Se7en, The Silence of the Lambs, Thomas Harris, Dean Koontz, or the kind of serial killer fiction that actually gets inside the killer’s head rather than just chasing him from the outside — this book was written for you.
If you prefer your thrillers light, cozy, or violence-adjacent, look elsewhere. This one doesn’t apologize for what it is.
The 4MK Series — Where To Go After You Finish
The good news about finishing The Fourth Monkey is that it’s the first book in a trilogy. If you’re exploring J.D. Barker books in order, the sequence runs:
The Fourth Monkey (2017) — Start here. Always start here. The Fifth to Die (2018) — The stakes double. The psychology deepens. The Sixth Wicked Child (2019) — The highest rated book in the entire series. The conclusion that readers say made the whole trilogy worth every sleepless night.
Do not skip ahead. Do not start with book two. The reading order matters enormously with this series — each book builds on the emotional and narrative foundation of the last in ways that only pay off if you’ve lived through the previous volume.
Beyond the 4MK trilogy, Barker has built one of the most diverse and compelling backlists in modern thriller fiction — from the supernatural gothic horror of Dracul to his blockbuster collaborations with James Patterson. But the 4MK series remains the work that defines him. And The Fourth Monkey is where that definition begins.
Final Verdict
The Fourth Monkey is the rare thriller that does exactly what it promises and then exceeds it. It’s clever where it needs to be clever, brutal where it needs to be brutal, and emotionally resonant in ways you don’t expect from a serial killer novel. The dual timeline structure is masterfully executed. The pacing is relentless. The twist earns every bit of the reaction it produces.
James Patterson himself called it a thriller that “never disappoints.” The Daily Mail compared it to Thomas Harris’s Red Dragon. Heather Graham called it “everything a thriller should be.”
They’re all right.
Rating: 9/10
If you’ve been on the fence about J.D. Barker — this is the book that gets you off it. Read it. Then immediately order The Fifth to Die because you’re going to want it ready when you turn the last page.
Want to know more about J.D. Barker’s full body of work, upcoming releases, and where he sits in the thriller genre today? Check out the full feature on Vents Magazine: 👉 The Thrillers That Stay With You — And Why J.D. Barker Keeps Showing Up In That Space
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