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thriller
Series · thriller
4MK Thriller
The 4MK Thriller series by J.D. Barker has 4 known books (4 published) and is best read in publication order, starting with The Fourth Monkey (2017). The latest book with a fully recorded publication date is The First Scarlet Door.
- Books
- 4 known books (4 novels)
- Published
- 4
- First published
- 2017
- Status
- ongoing
- Shelved under
- Thriller
- Last checked
Start here: The Fourth Monkey (2017) — then read straight through in publication order.
Reading order
The date order of published books and any announced future entries — the default way to read the series.
- Book 1:
The Fourth Monkey
The Fourth Monkey (2017, 448 pages) opens the trilogy with 4MK apparently dead in a hit-and-run, forcing Chicago homicide detective Sam Porter's team to work backward through decades of the killer's diary pages to find a captive girl before she starves.
Alternative text for cover: Cover of The Fourth Monkey - Book 2:
The Fifth to Die
The Fifth to Die (2018, 544 pages) is the second entry, widening the hunt into a copycat plot that implicates Sam Porter's own past, continuing J.D. Barker's split narration between Porter's procedural chase and the killer's journal entries.
Alternative text for cover: Cover of The Fifth to Die - Book 3:
The Sixth Wicked Child
The Sixth Wicked Child (2019, 624 pages) is the longest entry in 4MK Thriller, closing the trilogy by finally answering who 4MK really was and why -- the book that made Barker's name as a bestselling thriller writer in his own right.
Alternative text for cover: Cover of The Sixth Wicked Child - Book 4:
The First Scarlet Door
The First Scarlet Door (2026, 352 pages) opens a new prequel trilogy that extends the series backward into 4MK's origins. It's set before The Fourth Monkey, though Barker wrote it to be read last by anyone who wants the central mystery to unfold in its originally paced order.
Alternative text for cover: Cover of The First Scarlet Door
The order the story's events happen in, novellas slotted where they belong.
- Book 1:
The First Scarlet Door
The First Scarlet Door (2026, 352 pages) opens a new prequel trilogy that extends the series backward into 4MK's origins. It's set before The Fourth Monkey, though Barker wrote it to be read last by anyone who wants the central mystery to unfold in its originally paced order.
Alternative text for cover: Cover of The First Scarlet Door - Book 2:
The Fourth Monkey
The Fourth Monkey (2017, 448 pages) opens the trilogy with 4MK apparently dead in a hit-and-run, forcing Chicago homicide detective Sam Porter's team to work backward through decades of the killer's diary pages to find a captive girl before she starves.
Alternative text for cover: Cover of The Fourth Monkey - Book 3:
The Fifth to Die
The Fifth to Die (2018, 544 pages) is the second entry, widening the hunt into a copycat plot that implicates Sam Porter's own past, continuing J.D. Barker's split narration between Porter's procedural chase and the killer's journal entries.
Alternative text for cover: Cover of The Fifth to Die - Book 4:
The Sixth Wicked Child
The Sixth Wicked Child (2019, 624 pages) is the longest entry in 4MK Thriller, closing the trilogy by finally answering who 4MK really was and why -- the book that made Barker's name as a bestselling thriller writer in his own right.
Alternative text for cover: Cover of The Sixth Wicked Child
About the 4MK Thriller series
The 4MK Thrillers follow Chicago homicide detective Sam Porter's hunt for the "Four Monkey Killer," a methodical murderer who poses victims in a grim echo of "see no evil, hear no evil, speak no evil" before adding a signature fourth twist of his own. J.D. Barker splits each novel's narration between Porter's procedural chase and the killer's own journal entries, so the reader works the same case from both sides of the crime-scene tape at once. The Fourth Monkey opens with 4MK apparently dead in a hit-and-run, forcing Porter's team to work backward through decades of diary pages to find a captive girl before she starves; The Fifth to Die widens the hunt into a copycat plot that implicates Porter's own past; The Sixth Wicked Child closes the trilogy by finally answering who 4MK really was and why.
Barker builds each book around a structural trick — footnotes, timestamped journal pages, competing first-person voices — that turns the act of reading into part of the puzzle rather than just a way of delivering it. The trilogy made Barker's name as a bestselling thriller writer in his own right, well before his run of James Patterson collaborations, and remains his most acclaimed original work. A prequel trilogy beginning with The First Scarlet Door extends the series backward into 4MK's origins.
Frequently asked questions
How many books are in the 4MK Thriller series?
Three novels make up the original trilogy -- The Fourth Monkey (2017), The Fifth to Die (2018) and The Sixth Wicked Child (2019) -- plus a 2026 prequel, The First Scarlet Door, opening a planned prequel trilogy.
What order should I read the 4MK books in?
Publication order for the main trilogy: The Fourth Monkey, The Fifth to Die, The Sixth Wicked Child. The prequel The First Scarlet Door is set earliest in the story's internal chronology but was written and released after the trilogy.
Who is the 4MK killer?
"4MK" (the "Four Monkey Killer") is the case's working name for a Chicago serial murderer whose real identity is the trilogy's central mystery -- naming it here would spoil the ending of The Sixth Wicked Child.
Is the 4MK trilogy connected to J.D. Barker's other novels?
No. It's a self-contained case for detective Sam Porter, separate from Barker's other solo novels like Dracul and Forsaken, though all share his taste for unreliable narrators and journal-style structure.
Is The First Scarlet Door a sequel or a prequel?
A prequel -- the first book in a planned prequel trilogy set before the events of The Fourth Monkey, following 4MK's origins.
If you like the 4MK Thriller series
Reading order last verified .