The Castle: A Lancashire Detective Mystery

DCI Walker Crime Thrillers #5

by J.J. Richards

From an Amazon #1 International Bestselling series! 📚🥇

Over a quarter of a million series copies sold.
10,000+ series ratings across all platforms – averaging 4.4 out of 5. ⭐⭐⭐⭐⭐

A series that has previously reached #1 in the Amazon Kindle Free Charts (United States, Canada and the United Kingdom), and ranked #1 in multiple paid Kindle crime fiction categories.

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THE

"A timely and intense detective thriller" — SRP Editorial Review

A body on display
A message written in blood
And a puzzle that defies logic

DCI Jonathan Walker thought he’d seen it all—until a case in Lancaster forces him to read old crimes anew. When baffling clues surface in the city’s oldest institutions, Walker must navigate a web of secrets, public fury, and a riddle that won’t stay solved. Every answer seems to raise more questions, and the closer he gets, the more the stakes tighten.

Atmospheric, propulsive and quietly unsettling, The Castle is a masterful police procedural that blends meticulous detective work with a slow-burn mystery. Perfect for readers who love tense, character-driven thrillers where history casts a long shadow.

Step into the dark heart of Lancaster. But beware what you might uncover.

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🎧 Add the audiobook at a reduced price with Amazon Whispersync — just tick the “Add audiobook” box under Buy Now. Read or listen anytime — it always picks up exactly where you left off, or follow along as it’s narrated.

What readers are saying
“A riveting thriller”
“Highly recommended”
“Difficult to put down”
“This is a stunning story”
“Brilliant series!”

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Fans of Ann Cleeves, Peter James, LJ Ross, Rachel McLean and Wes Markin will devour this one.

The Castle is the fifth book in the DCI Walker Crime Thrillers, a bestselling British detective series set across Lancashire and the North West of England.

Available in e-book, paperback and audiobook.

Each book can be read as a standalone case, but the full story is best enjoyed in order.

👉 Stay with Walker as the investigation reaches its most unsettling turn yet.

Genres: Mystery, Audiobook, Thriller

320 pages, Kindle Edition

Published October 7, 2025

Reviews

[Amy · Rating 5 out of 5]

Out of all five DCI Walker books, this is my favorite. It opens with the murder of a trans person. During the investigation, Walker admits he does not fully understand gender fluidity, but he keeps an open mind and focuses on the victim’s right to justice. Further in the investigation, he encounters a man with physical and cognitive disabilities. Again Walker learns the man is a complete person, much more than how society perceives him. The description of their ongoing relationship was so tender, I had tears in my eyes.

The author has developed the character of Walker as a man with flaws. But he is also someone who wants to learn and grow, and as he does, he only becomes a better detective.

[Ted Barringer · Rating 1 out of 5]

I've read all 5 Detective Walker books, this one is no better or worse than the others. Why then a 1-star rating. Because I am sure the publishers pressured Mr Richards to needlessly insert an LGBTQ++ character. The character's tansitioning moved the story, not at all. Indeed, I love it when writers forced down this rabbit hole immediately kill off the LGBTQ++ character with never another thought. All but Stephen King that is, he kills them first no doubt, but no publisher forces him to write these people in, he does because is is all in on Wokeness. I digress, if you got this far, read the book, if for no other reason, than to get to the next one.

[Christine Rennie · Rating 5 out of 5]

The Castle by JJ Richards is book 5 in the DCI Jonathon Walker Lancashire police series. This time the crime is set in Lancaster with a body on display that defies logic.The murders mount up but the puzzle is waiting to be solved. This is a murder scene based on the witches trial in 1612 and numbers and puzzles need to be so solved before everything is made clear and all deaths are accounted for.
A creepy, unnerving and unsettling story about the Lancashire witches but based on murders in the present day.
Highly recommended

[Philip Robinson · Rating 4 out of 5]

A riveting thriller

The author has done it again - produced an unique novel. Such a well researched book. I was there following the investigation - totally involved as the story unfolded. Brilliant characterisation and descriptions. Very authentic backdrop takes you there. My only gripe was that there appeared to be too much padding. Several observations in the narrative were repeated again and again but worded different. Otherwise this is an excellent book.

[Mrs G · Rating 5 out of 5]

My first time reading a book by this author. I thoroughly enjoyed it. Set around Lancaster Castle it revolves around the Witches of Pendle, and retribution for the grisly way that they were executed. I enjoyed the whole book, particularly because we had friends who were born and lived in that area, Pendle Hill. Very devious clues left by the murderer, a severely disabled man seeing the happenings at the castle. Well worth the read, I am now starting the next book in the series..

[Martin Devine · Rating 5 out of 5]

I’ve read the first 4 books and enjoyed them all. As with the others, this one had a good pace, easy to read, set in Lancashire where I live and the main characters (police) are ones you want to root for . The plot is interesting, contains topical content eg use of AI. I have book number 6 ready to read. I recommend this series. Good work JJ Richards.

[Caroline · Rating 5 out of 5]

Loved this, another great book featuring DCI Walker, this time with his team investigating a series of murders linked to witch trials over 400 years earlier.
Great plot, good pace and well developed characters. What more could you want!

[sandra arthur · Rating 5 out of 5]

Really good

This was really good. Definitely kept you wanting to keep reading on and on. Quite a surprise to hear the evil doctor rear his menacing persona again. Obviously we haven't heard the last of him. Highly recommended.

[Debbie · Rating 5 out of 5]

I hope JJ Richard continues this series of Lancashire Detective Mysteries and at some point we find out who really killed DCI Walker's sister!

[Hugo Collingridge · Rating 3 out of 5]

A fun and engaging murder mystery, with a compelling villain. I will have to read more Detective Walker novels now.

[Susan · Rating 4 out of 5]

A body is found hanging from the Lancaster Castle walls. Now DCI Walker and his team have a murder and a puzzle to solve. Will they do so before the next death.
An entertaining modern mystery