4MK Thriller · Book 4

The First Scarlet Door

by J.D. Barker

Published
22 September 2026
Pages
352
ISBN-13
9798999350947
Type
novel

Buy on AmazonAll 4MK Thriller books in order

Cover of The First Scarlet Door

About this book

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.

Its place in 4MK Thriller

The First Scarlet Door is book 4 in the 4MK Thriller series. It follows The Sixth Wicked Child. See the full 4MK Thriller reading order.

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…

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