Mr Killjoy: An Absorbing British Crime Thriller

Luke Sackville Crime Thrillers #9

by S J Richards

The Luke Sackville Crime Thriller series continues…

Beware the bearer of false gifts

Luke Sackville’s Ethics Team is stretched to breaking point across several investigations, little realising that one man links them all.

Narcissistic, cunning and ruthless, Mr Killjoy is reaping the rewards of cybercrime, and is indifferent to the fact that his victims are being driven to despair and beyond.

Luke connects the dots and begins to home in, but as the villain is cornered he strikes out and none of the team is safe.

Mr Killjoy is the ninth book in the series of crime thrillers featuring ex-DCI Luke Sackville and his Ethics Team. It’s perfect for fans of JD Kirk, LJ Ross, Jack Gatland, Alex Smith, TG Reid and JM Dalgliesh.

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What people are saying about the Luke Sackville Crime Thriller

"⭐⭐⭐⭐⭐ I’m really enjoying this series and it gets better with each book. The characters are terrific. Well paced and some laugh out loud moments."

"⭐⭐⭐⭐⭐ So glad I came across SJ Richards, he's definitely rising up there as one of my favourite authors."

"⭐⭐⭐⭐⭐ Very well written, fast plot and extremely likeable characters. I would 100% recommend this series and author to any fan of the crime fiction genre."

"⭐⭐⭐⭐⭐ I’d highly recommend this to anyone who loves crime novels. I’m loving this series."

"⭐⭐⭐⭐⭐ This is a brilliant crime suspense series and I'm really looking forward to the next instalment."

"⭐⭐⭐⭐⭐ I'm absolutely loving this series - the writing is brilliant - the characters a joy and the storylines full of suspense and intrigue."

354 pages, Kindle Edition

Published August 5, 2025

Reviews

[Emma · Rating 4 out of 5]

Thanks for the ARC, I finished it in one go!

Mr Killjoy, the ninth installment in S.J. Richards’ gripping crime thriller series, proves once again that this author knows how to keep readers on edge—and entertained. Centered around the ever-compelling Luke Sackville, this latest case dives deep into the murky world of cybercrime, exposing the many faces of digital threat: from ransomware attacks to phishing schemes, deepfake and the sinister workings of the dark web.

Luke Sackville remains one of the most engaging protagonists in the genre—smart, sharp-witted, and a natural leader. The returning cast of characters is as strong as ever, with their familiar quirks, jokes and loyalties bringing warmth and depth to a story that doesn’t shy away from its darker elements. There are moments of violence and tension, yes, but also flashes of dry wit and banter that provide a well-timed counterbalance.

What stands out in Mr Killjoy is how S.J. Richards handles the cybercrime theme—not just as a plot device, but as a reflection of modern anxieties. The novel raises real questions about privacy, security, and how vulnerable we are in an increasingly connected world, all while delivering a fast-paced and twist-laden narrative.

Nine books in, and S.J. Richards still delivers the goods. Mr Killjoy is clever, timely, and packed with enough grit, suspense, and character charm to satisfy loyal fans and newcomers alike.

Mr Killjoy is a cybercrime thriller that bites.

[Maureen · Rating 5 out of 5]

Mr Killjoy by S J Richards is book 9 in the Luke Sackville series. Each time I start a new book in this series, I am eager to see what the characters are up to. They have become like friends and I’m keen to get involved in their lives again. Mr Killjoy is about scammers and the dark web, so very topical. And the person behind this scam is Mr Killjoy. Luke is approached by Avon and Somerset Police and the National Cyber Crime Unit to help in their investigation. However, they are interrupted by an emergency. The characters are wonderful and so varied. Glen Baxter seems to be incompetent, and you wonder how anything gets done in his area until, in an emergency, he shows another side. Josh is a funny character, immature in some ways, but very smart in others. You can’t help but like him and he looks to Luke as a father figure. Luke continues to steer his Ethics Department at Filchers and the team all look up to him. He is very steady and takes everything in his stride. And we have the return of Misty Mitchell, the PI, and what a character she is. Loved the mention of TG Reid’s DCI Bone as Bruce is listening to one of his audiobooks. Such a fabulous read and reading the Afterword was very enlightening as it talked about different scams that have happened over the years.

[Alyson Read · Rating 5 out of 5]

Mr Killjoy lives up to his fictitious name and is certainly responsible for making a lot of people’s lives miserable. The creator of a number of cybercrime tools, together with his three associates, is making a lot of money selling subscriptions to these programs, such as FishIt and PayIt, on the dark web and this is the new case for head of the Filchers Ethics team ex-DCI Luke Sackville. Brought to Filchers’ CEO Ambrose’s attention by the new ACC Jean Scarrott and an NCA operative, is the discovery that the criminal is one of their employees and eventually they narrow down a number of suspects. Meanwhile other cases, including an attempted suicide amongst the staff and fraudulently obtained payments are being dealt with by others in his team. As the cases converge, how can Luke, along with Sam, Josh, Maj and Helen, former colleague DI Pete Gilmore and some very effective outside help, force Mr Killjoy out from under his cloak of darkness and anonymity without anyone else getting hurt? They have already seen what he is capable of and fear that he will strive to protect his identity at all costs.
This story features a great twisty plot with absolutely loads going on and some very topical crimes. It was great to see return appearances from the superb PI Misty Mitchell, as well as DI Pete Gilmore and a new face at the station, whilst Glen, Josh and Edward Filcher are at their hilarious bests once again. I love the description of Glen as “an overnourished rhino” and his vocabulary is even funnier, although we do see a very commendable side from him this time. I have read this series since the publication of the very first story and would definitely encourage other readers to start at the beginning to see how this very special and loveable cast of characters have grown together as a team. As Josh would say, looking forwardo mucho to book 10!

[Deb · Rating 5 out of 5]

Well, here we are again book nine in the Luke Sackville Crime Thriller series & what a pleasure it is to be in the company of the Filchers’ Ethics Team. I love these books & the characters draw you in - not just the main ones but those on the periphery too.

After a heart wrenching opening chapter, Luke & his team are front & centre once more. There are several ongoing investigations including sexploitation, bogus invoicing & deepfake video calls which are all cybercrimes. It becomes apparent that all the cases are linked by one individual, the eponymous Mr Killjoy & he appears to work at Filchers.

I think this is my favourite book in this series - brilliantly crafted with all the threads being pulled into a very satisfying conclusion. Of course, there are lighter moments - Edward Filcher is an absolute scream, Josh is adorable & Glen is a Mrs Malaprop for the 21st century. You really should read all these books in order, we have now reached the stage where the cast’s backstories are not only recommended but required to understand why they are such a cohesive team. Having a meander through the streets of Bath is always a joy & you could do worse than listen to the same audio book as Luke too (T G Reid). Next one please Mr Richards. Gucci!

[Lynda · Rating 4 out of 5]

Book 9 of the Luke Sackville Crime Series set in Bath. Can be read as a stand alone but better to read the previous books to understand the background to the Ethics team at Filchers. This time there is a cybercrime expert to find. They are believed to work at Filchers and Luke’s team are asked to try and discover who it is.

Briefly, unfortunately just as the team open their investigation there is a fire at Filchers resulting in 3 deaths. The person behind the cybercrimes is known as Mr Killjoy and he is responsible for a number of cybercrimes from phishing schemes to illicit activities on the dark web, with no sympathy for the victims of his crimes.

With the team working on a number of other cases, as Luke begins to put the clues together it seems that there is some convergence. I love this team and the plot is very timely; there can’t be many people who don’t worry about digital privacy and potential scams. I know I do. With such a diverse range of delightful characters this is an easy yet entertaining read. Great fun, bring on the next chapter. 4.5⭐️

[Martha Brindley · Rating 5 out of 5]

This is the ninth book in the series featuring ex DCI Luke Sackville and it felt like catching up with old friends. I really recommend the whole series to fans of crime thrillers, it is one of my favourites in the genre. The cast of characters are so diverse, with all their different personalities and foibles, and some good banter between the Ethics Team. This is a very clever, well written read which features some topical aspects of our modern society. Cyber crime, phishing schemes and the dark web are all expertly researched by the author and cleverly woven into a tale filled with action and suspense. The nod to TG Reid's DCI Bone, another one of my favourite characters, is a nice touch from the author. Another brilliant and easy 5* read from the author, long may the series continue please!

[Mary Ryan · Rating 5 out of 5]

It's great to be back with Luke and the team. This time the team get involved with the cybercrime side of things. I marvelled at how devious some people are and the extravagant methods involved to extract money from people. Even worse, the impact of such schemes was really brought home to me while reading this.

I really enjoyed how the team worked together to handle separate parts of the same investigation. There is a really welcome return of Misty, a larger than life private investigator. She always adds some colour and humour to things, and I love her character. Not that there's any shortage of humour here anyway. Josh provides plenty of that all by himself! There's several twists and when it seemed things had all come to a head, there was time for more. This was yet another compelling and riveting read and I can't wait for the tenth one to come along.

[Michelle · Rating 5 out of 5]

Mr Killjoy is the ninth book in the ex-DCI Luke Sackville and the Ethics team at Filchers. I am looking forward to catching up with the members of the team.
The time the team have a complex case which involves cybercrime, phishing and using the dark web which involves someone that works at Filchers and a young person at Filchers that has got caught up in it, which ended him trying to take his own life.
Yet again this is another fantastic read by S.J. Richards. Another cleverly written storyline and a modern take what happening today’s society and will keep you guessing to find out who Mr Killjoy is. This lots of action and the great characters and I love the humour between the Ethics team and with Josh up to his old tricks again. I will look forward to the next instalment. 5 stars from me.

[Debra Boyle · Rating 5 out of 5]

The next in this great series that I am lucky enough to be an ARC reader for.

This book was so interesting and current - cybercrime. This was a great read - exploring areas of cybercrime that is mentioned every day in talk shows. Fascinating insight into this dark world.

I love how the book takes us through the storylines leading as always to a twist at the end. !

It’s great how working in Ethics with Luke’s background makes such an interesting career ! Such diverse and interesting subjects !

As always I love the interactions of the characters and how they develop and as always - Josh - love his character - laugh out loud moments.

All I can say is it’s such a great book and I look forward to the next one.

I don’t do spoilers but the last few chapters were so thrilling with twists and turns. Just phew !

Try these books - love them !

[Sylvia Bland · Rating 5 out of 5]

Mr Killjoy is the ninth book in the Luke Sackville series. This time Luke and his team from the Ethics department at Fichers are asked to investigate the attempted suicide of a new and young employee. In doing so it opens up a whole can of worms when it is discovered that an unknown member of staff, calling himself Mr Killjoy, has set up various unethical websites to exhort money and cause pain, distress and even death. Who is Mr Killjoy and can Luke and his team stop him before any more deaths occur?
This series gets better with each book, and I love that all the characters on his team have an ongoing story of their own which are brought to life in each book.
This book can be read as a standalone, but once you've read it, I guarantee you'll want to start reading from the beginning.
Definitely worth a read.

[Dee (readaholic_dee) · Rating 5 out of 5]

An absolutely fantastic read. Highly recommend this series.

I was so excited to get back in the lives of Luke and his team. S J Richards portrays his characters so well, that when the next book in the series appears I cannot wait to find out what's happening with them all and what scrapes they are going to get in, Josh especially, he is now one of my favourites.

This book delves into the world of the dark web and online scammers. I found it really engaging, highly informative, and genuinely intriguing. S J Richards certainly knows how to write a book that draws you in.

The book is well written, with a nice pace that keeps you turning the page. With a highly addictive set of characters that you cannot help getting involved with.

Happy Reading.

[SkyeWake · Rating 5 out of 5]

Another absorbing instalment in this excellent series. With the advent of AI and its sudden emergence into all areas of our lives, this story is absolutely relevant to things happening across the globe. We’re all told to be wary of phishing emails, but just how easy is it to fall into the trap of one of the many cyber attacks? Luke and his team are investigating who is behind a network of AI criminal enterprises when it becomes even more serious when their headquarters is attacked and people are murdered. It’s a race against time to unmask the kingpin.
I have an interest in IT anyway, so I found it slightly scary just how AI can be used in criminal activities, but it made it all the more readable for me.

[Chris · Rating 4 out of 5]

⭐️⭐️⭐️⭐️ Mr Killjoy - SJ Richards

Soooo good to be back with Luke’s team at Filchers - and if you’re a fan of this series, you’re going to love it.

Steve’s books really shine when they’re steeped in the real world - and the FraudGPT industry provides plenty of inspiration for Steve to draw upon. So many people are at risk of these ‘scams’ whether it be Sexploitation, Deep Fakes, QR code frauds - so it’s the perfect backdrop for a tense and pacy crime read!

These characters are so familiar now - and I’ve still got plenty of rooting to do for a couple of them and how their stories play out - so don’t leave us hanging too long Steve……next book needed NOW!

[Tracey · Rating 5 out of 5]

Book 9 in the series and what a welcome addition it is. Being Reunited with Luke Sackville and the Ethics team is always a good thing. The characters and their relationships continue to develop book after book. within the first few pages it's like being home. This instalment features cybercrime, phishing scams and the dark web, throw in some tense moments, along with twists and turns to keep you guessing and a sprinkle of returning characters that have a fantastic way with words (#mistymitchell!). This is a fantastic read as a standalone, but even more satisfying as part of the series.

Huge thanks to SJ Richards and Netgalley for my ARC.

[Cathy · Rating 5 out of 5]

A real page turner that kept me guessing until near the end. I love the diverse cast of characters headed up by the smart, warm and charismatic leader Luke Sackville. This time the team is dealing with cyber crime with its many different iterations. Another very topical and fascinating subject. There is plenty of action and tension but also some welcome humour. It was nice to see some returning characters like Misty, the no holds barred PI that contributes her talents to the team. I recommend reading the whole series in order to fully appreciate the development of the characters.

[Myra McCulloch · Rating 5 out of 5]

This is book 9 in the Luke Sackville series, and once again, no disappointments.
I read this in 1 sitting and the regular characters are like catching up with old friends.

Another gripping thriller with Luke and his team involved in investigating a raft of crimes all tied back to cybercrime. Eventually extortion, theft, murder, kidnapping, and arson all come to the fore as they hunt for Mr Killjoy.

Laced with humor and plot twists that keep you on the edge of your seat makes for entertaining reading.

[Karen McGrath · Rating 5 out of 5]

Mr Killjoy by S J Richards is the ninth book in the Luke Sackville series.
Ex DCI Luke Sackville and his ethics team are asked to investigate a complex cybercrime linked to someone working at Filchers. It’s a fast paced story with lots of unexpected twists and turns and with the usual humour from Josh and Glen. It’s a brilliant series, highly recommended, but read the books in order starting with Taken to the Hills to understand the developing backstory and characters.

[Ruth Matheson · Rating 5 out of 5]

The topic of this book is one which is rife worldwide at the moment - that being internet scams and the dark web. The author seamlessly joins these with the ethics team's other investigations and as usual, we also have attempted murders and a wee bit of love along the way. We all know a Filcher and a Glen in real life and that adds to the story as well. Great page turner and an addictive read. This series is one of my favourites !

Thanks to the author for the ARC to review.

[Caroline Lawman · Rating 5 out of 5]

A cybercrime story that I could get on board with. I’m not very techy minded and have swerved away from this type of book in the past. However, having read all the previous Luke Sackville books I had to read this one too. Loved it. Has the edge of the seat storyline like the previous books. Great characterisation as always. Excellent backstories and plenty of humour. I think the next book should include a conversation between Josh and Glen! I’ll never enter a building without looking for the ‘trembly’ points again! Keep them coming Steve.

[Jane Hill · Rating 5 out of 5]

Enjoyed this exciting book - Mr Killjoy kept me guessing until the end. With many modern, and frightening, subjects covered with relation to cyber crime, the book delves into the world of the dark web and the terrible way it affects people. Luke and his ethics team help the police in solving who is causing mayhem all round. Josh continues to amuse with his original expressionals!!! Highly recommended

[John Hinchliffe · Rating 5 out of 5]

Audio book version...
Mr Killjoy by SJ Richards.
Hold on tight, this is a terrific ride! Steve Richards has done it again, delivering excellent characters and a gripping story. The plot feels scarily realistic as Luke and his team dive into the world of cybercrime, something that’s all too relevant today. It’s a real page-turner (or in this case, a can’t-stop-listening experience), made even better by Sam James’s brilliant narration. A very enjoyable listen, and I can’t wait for book 10!

[Jane · Rating 5 out of 5]

Once again I loved the latest book in this series. The plot was intriguing with many strands which seem unconnected but are skilfully woven together at the end. The team dynamic continues to get stronger and it’s great to see their personal lives developing. I enjoyed Glen being involved in some action and seeing a different side to him and Misty once again is a delight. The humour is, as always brilliant with some, much needed laugh out loud moments.

[Nancy Fagan · Rating 5 out of 5]

The Luke Sackville story continues in Mr. Killjoy. This book is what you expect from the author. It has a bit of romance, humor and plenty of clues leading you down many paths while trying to guess who the villain is. Well worth reading.
I received an advance copy of the book for free, and I am leaving this review voluntarily.

[Kaz H · Rating 5 out of 5]

Well I was really looking forward to the latest instalment of Luke and his team and I was not disappointed. Cyber crime is the big problem for the ethics team and it comes with many problems and worries. Lives are at risk and money plays its part. As usual Josh gets mixed up with some funny results.
All in all a good read and looking forward to where we go next.

[Lindy Protzek · Rating 5 out of 5]

It's great to be back with Luke and the team. I love that they are working on a Cyber Crime this time. It's truly amazing the things criminals can come up with to scam people through the world of Cyber crime, pretty scary actually. As usual the characters of this team are funny, endearing and thoroughly intriguing. Great book. I highly recommend this series.

[Val Newton · Rating 5 out of 5]

Mr Killjoy - a one man cybercrime tornado, is stretching Luke and his wonderful Ethics Team to its limits. Offering a range of cybercrime scams to unscrupulous criminals, Mr Killjoyis hard to identify, but Luke and his team love a challenge. With a very real subject matter, relevant to our current climate, this ninth instalment is both absorbing and informative. A brilliant read

[Susan · Rating 5 out of 5]

9 books in this fantastic series already.
Each one focuses on a different aspect of criminal activity.
Mr Killjoy is a scary offering about the world of cybercrime and deep fake technology.
It shows how easy it is to blackmail vulnerable victims.
What is going to be next from the mind of SJ Richards ?

[Jennine Oldis · Rating 5 out of 5]

I am invested in this series with Luke and his team as I want to know what they are up to and this latest battle with Mr Killjoy was a little bit more sinister than normal. There was a lot more complexity to this case and while Luke was looking one way, Sam, Maj and the team were being drawn into a dark world of cybercrime. Enjoyable as always so eagerly awaiting the next one!

[Zara · Rating 5 out of 5]

WOW! Steve has gone and done it again with Luke and the team.

From cyber crime, to arson, murder and the kidnapping, this is an absolute whirlwind of a pageturner!

All the AI involved for someone to create multiple websites to gain, hundreds of thousands of pounds, racking upto millions in fraud investment. And then to throw Harry Potter quirks in.. Had me hooked in from the beginning as always.

I really love how close the team are and how they work so well together.

Sam & Luke are definitely meant to be together :)

[Gillian Morris · Rating 5 out of 5]

Another excellent instalment in this great series about Luke and his ethics team at Filchers. Comedic moments aplenty in book 9. An engaging storyline and well written enjoyable characters make this hard to put down. I can’t wait for the next book.