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Kat and Lock #4
Body of Lies
The brand-new thriller featuring DCS Kat Frank and AIDE Lock from the award-winning and Sunday Times bestselling author of In the Blink of an Eye .
PRAISE FOR JO
'Terrifyingly timely and provocative' VAL McDERMID
'The most original crime novel you'll read this year' CLARE MACKINTOSH
'Just brilliant!' LISA JEWELL
'Sharp, perceptive writing and a brilliant new take on the detective duo' T. M. LOGAN
'Everything you could hope for in a heartbreaking, intelligent, deftly plotted and so original' FIONA CUMMINS
'A fresh take on the buddy-buddy cop trope . . . Provocative and compelling' VASEEM KHAN
'Wildly original, heartfelt, funny, and properly thrilling. Take a bow, Jo Callaghan' CHRIS WHITAKER
PRAISE FOR JO
'Terrifyingly timely and provocative' VAL McDERMID
'The most original crime novel you'll read this year' CLARE MACKINTOSH
'Just brilliant!' LISA JEWELL
'Sharp, perceptive writing and a brilliant new take on the detective duo' T. M. LOGAN
'Everything you could hope for in a heartbreaking, intelligent, deftly plotted and so original' FIONA CUMMINS
'A fresh take on the buddy-buddy cop trope . . . Provocative and compelling' VASEEM KHAN
'Wildly original, heartfelt, funny, and properly thrilling. Take a bow, Jo Callaghan' CHRIS WHITAKER
Hardcover
First published May 21, 2026
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Displaying 1 - 30 of 219 reviews
May 26, 2026
This is one of the best books I’ve read this year, maybe in several years. It made me feel everything, from chills, to deep sadness and sorrow. In addition to all I felt, it also made me think deeply about AI and some of the ethical issues raised, while feeling my pulse throbbing from the intensity of the plot. It was simply so much packed into a unique novel, and I’m crushed that the book is read and that it might be years before I read something like this again.
July 5, 2026
~4.25~
I didn't realize this would be the last book in the Kat & Lock series, and now I want to cry, not just because it's over but because of that ending. Stab me in the gut, why don't you, Jo Callaghan?
I didn't even trust Lock, but why, oh, why? Was there a shred of hope at the end? I think that's up to each reader to decide. But I think we can all agree that
This is a politically charged novel, and why wouldn't it be? AI is politically charged. Is AI taking our jobs? Stealing our creativity? Becoming too powerful? Hell if I know, but I think this is just the tip of the iceberg. We're on the brink of a revolution.
This series is set in England, but the tension between the old-school diehards and "tech bros" is the same everywhere. Substitute "U.S. senator" for "UK MP," and you have yourself the same story but in America.
The first half took me a few days to get through. It wasn't boring by any means, but the tension just wasn't there. Until it was ... I binged the second half in a couple hours, pulling a late-nighter and sleeping through my alarm. Worth it!
A final thought: I don't know that I've read a book where the death of a spouse and the overwhelming grief that follows was handled as tenderly and realistically as it was in this series. The protagonist, Kat, lost her husband to cancer, as did the author, as did I. Such a visceral, earth-shattering loss translates into your every though, every moment, every breath.
Thank you, Ms. Callaghan, for not painting over this devastation with pretty colors.
I can't wait to see what this author does next. I hope she has another series in the works, because this one was damn good.
I didn't realize this would be the last book in the Kat & Lock series, and now I want to cry, not just because it's over but because of that ending. Stab me in the gut, why don't you, Jo Callaghan?
I didn't even trust Lock, but why, oh, why? Was there a shred of hope at the end? I think that's up to each reader to decide. But I think we can all agree that
This is a politically charged novel, and why wouldn't it be? AI is politically charged. Is AI taking our jobs? Stealing our creativity? Becoming too powerful? Hell if I know, but I think this is just the tip of the iceberg. We're on the brink of a revolution.
This series is set in England, but the tension between the old-school diehards and "tech bros" is the same everywhere. Substitute "U.S. senator" for "UK MP," and you have yourself the same story but in America.
The first half took me a few days to get through. It wasn't boring by any means, but the tension just wasn't there. Until it was ... I binged the second half in a couple hours, pulling a late-nighter and sleeping through my alarm. Worth it!
A final thought: I don't know that I've read a book where the death of a spouse and the overwhelming grief that follows was handled as tenderly and realistically as it was in this series. The protagonist, Kat, lost her husband to cancer, as did the author, as did I. Such a visceral, earth-shattering loss translates into your every though, every moment, every breath.
Thank you, Ms. Callaghan, for not painting over this devastation with pretty colors.
I can't wait to see what this author does next. I hope she has another series in the works, because this one was damn good.
January 15, 2026
What a way to end the series!
May 31, 2026
Loved the book, loved the series, and gutted it's all over
July 1, 2026
*A Deadly Attack*
**4.5 Stars**
This is the fourth and final book in the ‘Kat and Lock’ series. A police procedural, it explores the integration of an AI detective, Aide Lock, into the police force.
The book seems to conclude the series, offering a fresh perspective on AI’s application. DCS Kat Franks leads a small team called the Future Policing Unit (FPU).
On Halloween night, an MP is murdered. A peculiar message in binary code is left specifically for Kat and Lock. ‘Catch me if you can’ they will later see that this is more than a clue.
This MP was a vocal opponent of AI. As the post-mortem progresses, the murder weapon turns out to be a deadly chemical. Kat and Lock’s investigation soon plunges them into the world of politics and a cyberattack demanding ransom.
The attack also targets the national grid, affecting the entire country. Kat and Lock must uncover the truth, but they’re hampered by being confined with MPs and having limited technical access.
As lives hang in the balance, one of them connected to the team, Kat faces an impossible choice. Naturally, the finger is pointed at the wrong suspect.
Social media posts are full of speculation and I found them particularly annoying, especially the ignorance in the messages until the power went out. We also learn whether Lock, despite his advanced learning, can think independently.
This cracking series is a must-read, and I’ll likely revisit it back-to-back.
**4.5 Stars**
This is the fourth and final book in the ‘Kat and Lock’ series. A police procedural, it explores the integration of an AI detective, Aide Lock, into the police force.
The book seems to conclude the series, offering a fresh perspective on AI’s application. DCS Kat Franks leads a small team called the Future Policing Unit (FPU).
On Halloween night, an MP is murdered. A peculiar message in binary code is left specifically for Kat and Lock. ‘Catch me if you can’ they will later see that this is more than a clue.
This MP was a vocal opponent of AI. As the post-mortem progresses, the murder weapon turns out to be a deadly chemical. Kat and Lock’s investigation soon plunges them into the world of politics and a cyberattack demanding ransom.
The attack also targets the national grid, affecting the entire country. Kat and Lock must uncover the truth, but they’re hampered by being confined with MPs and having limited technical access.
As lives hang in the balance, one of them connected to the team, Kat faces an impossible choice. Naturally, the finger is pointed at the wrong suspect.
Social media posts are full of speculation and I found them particularly annoying, especially the ignorance in the messages until the power went out. We also learn whether Lock, despite his advanced learning, can think independently.
This cracking series is a must-read, and I’ll likely revisit it back-to-back.
June 23, 2026
Шкода, що авторка вирішила завершити цю серію саме так. З одного боку мені дуже подобається сама ідея, але втілення вийшло якимось занадто драматично-епічним. Не люблю коли в детективах приплітають політику, а особливо коли це виходить на національний чи міжнародний рівень. Занадто вже нереалістично мудровано вийшло.
June 12, 2026
Fourth and final book in the Kat and Lock series. For anyone that doesn't know Lock is a hologram that is working with the police. In this book DCS Kat Frank returns to work after the previous case. It's Halloween and a MP is found dead.
I really don't like giving this book two stars but out of series I felt this was the weakest. I felt that the story started off strong but I lost my interest half way through. I did persevere as I knew it was the final book and wanted to see how it was going to end.
I'm not a fan of police procedure but will read them if they have that something. This series had just that with Lock so the books for me became enjoyable overall.
Just because I didn't enjoy this particular book is did enjoy the series and would recommend it.
I really don't like giving this book two stars but out of series I felt this was the weakest. I felt that the story started off strong but I lost my interest half way through. I did persevere as I knew it was the final book and wanted to see how it was going to end.
I'm not a fan of police procedure but will read them if they have that something. This series had just that with Lock so the books for me became enjoyable overall.
Just because I didn't enjoy this particular book is did enjoy the series and would recommend it.
May 22, 2026
I’ve been a huge fan of this series, have loved every book and although I know every series does have a natural end, I’m so sad that this is the final outing for DCS Kat Frank and her hologram partner AIDE Lock.
Body of Lies begins a few months after the ending of Human Remains. Kat has returned home and to work but it is clear that she is still haunted by traumatic events and questions her own judgement at every turn. She is still heading the Future Policing Unit but the team are struggling. Her AI partner, AIDE Lock is again by her side, via the wrist bracelet Kat wears, but its quest for a human form makes Kat uneasy and as much as she relies on Lock, there are trust issues.
The murder of an outspoken MP, vocal against the development of AI, thrusts the team not only into an investigation to find a killer but when a cyberattack threatens the entire country Kat and Lock are against the clock to discover who is behind it before more lives are lost.
The author superbly navigates the emotional struggles of Kat and other members of her team, not only in dealing with trauma and loss but also showing a thought provoking view of both the benefits and dangers of the AI revolution which adds a level of relevance and authenticity.
The final part of the story was gripping and dramatic. With the suspense racking up, there was shock at the revelations and ultimately the sad realisation that this was indeed the end. Jo Callaghan has created a fantastic crime series that has both heart and intelligence, all with a touch of dark humour. I really took these characters to my heart and I shall miss them, especially Lock. It (I still want to say he) could be infuriating but there was an endearing quality too and I did enjoy the bond that formed between Lock and Kat. I look forward to seeing what comes next by this very talented author.
Body of Lies begins a few months after the ending of Human Remains. Kat has returned home and to work but it is clear that she is still haunted by traumatic events and questions her own judgement at every turn. She is still heading the Future Policing Unit but the team are struggling. Her AI partner, AIDE Lock is again by her side, via the wrist bracelet Kat wears, but its quest for a human form makes Kat uneasy and as much as she relies on Lock, there are trust issues.
The murder of an outspoken MP, vocal against the development of AI, thrusts the team not only into an investigation to find a killer but when a cyberattack threatens the entire country Kat and Lock are against the clock to discover who is behind it before more lives are lost.
The author superbly navigates the emotional struggles of Kat and other members of her team, not only in dealing with trauma and loss but also showing a thought provoking view of both the benefits and dangers of the AI revolution which adds a level of relevance and authenticity.
The final part of the story was gripping and dramatic. With the suspense racking up, there was shock at the revelations and ultimately the sad realisation that this was indeed the end. Jo Callaghan has created a fantastic crime series that has both heart and intelligence, all with a touch of dark humour. I really took these characters to my heart and I shall miss them, especially Lock. It (I still want to say he) could be infuriating but there was an endearing quality too and I did enjoy the bond that formed between Lock and Kat. I look forward to seeing what comes next by this very talented author.
June 12, 2026
I really enjoyed this series and I am sorry it is over but I wasn’t entirely convinced by the ending.
The idea of an AI detective is very interesting though and very relevant. Since I began this series I have been using AI more and more and I can see how an AI detective, while not in hologram form for a while, is not far away. In fact given we now use AI to generate ideas and sift through existing research I suspect it is already being used.
Having read the series, I just felt that sometimes things were being over-explained. It was perhaps for the benefit of those readers who have joined the series with this novel but it began to grate a bit. Kat’s grief is central to the series too but occasionally I wish it had not been always so spelt out. It is there, driving her forwards all the time and I just didn’t need to be told because I knew it was there.
But I am very sorry it is over!
The idea of an AI detective is very interesting though and very relevant. Since I began this series I have been using AI more and more and I can see how an AI detective, while not in hologram form for a while, is not far away. In fact given we now use AI to generate ideas and sift through existing research I suspect it is already being used.
Having read the series, I just felt that sometimes things were being over-explained. It was perhaps for the benefit of those readers who have joined the series with this novel but it began to grate a bit. Kat’s grief is central to the series too but occasionally I wish it had not been always so spelt out. It is there, driving her forwards all the time and I just didn’t need to be told because I knew it was there.
But I am very sorry it is over!
Review of advance copy received from Publisher
There are no spoilers here. I always make sure not to include any but as this is the final book in the series I wanted to make that explicit.
Body of Lies picks up from the events of that explosive ending to Human Remains. This is a unique police procedural series that is absolutely worth your time. I personally was foolish and ignored my friends’ praises of Callaghan’s debut In the Blink of an Eye. They told me I would love it, but being aware one of the detectives was AI, I assumed I would not get on with it. I see this criticism a lot, so if you are in the same boat then please know I wholeheartedly recommend this series and hold my hands up that I was very, very wrong.
Yes, there is an AI element to the series, but it’s done incredibly well and it’s about so much more than that. Kat is such a well-written character, so believably human and incredibly relatable. Heck, I even love (love to hate or hate to love?) Lock.
Body of Lies features DCS Kat Frank and her holographic assistant AIDE Lock as they investigate the murder of a local MP. At the scene, they uncover a hidden message that seems to be targeting them. The series feels timely and resonant, in real life earlier this year CrimeOwl AI launched to help investigators process thousands of files in minutes, making it easier to connect evidence, uncover hidden patterns and generate new leads. It’s no surprise that Callaghan pre-empted this in her novels, as she has a background as a senior strategist researching the future impact of AI on the workforce.
Throughout the series there has been ambiguity surrounding Lock. Is it possible for the AI to have its own alternative motives and do a Skynet? There’s a knife-edge uncertainty throughout and I loved the resulting tension.
As mentioned I won’t go into too much more of the plot to avoid spoilers. I will say that there was a part that gave me Fight Club vibes and that the ending was superb. What a ride this masterpiece series has been.
Thank you to Simon & Schuster for the proof copy.
Body of Lies picks up from the events of that explosive ending to Human Remains. This is a unique police procedural series that is absolutely worth your time. I personally was foolish and ignored my friends’ praises of Callaghan’s debut In the Blink of an Eye. They told me I would love it, but being aware one of the detectives was AI, I assumed I would not get on with it. I see this criticism a lot, so if you are in the same boat then please know I wholeheartedly recommend this series and hold my hands up that I was very, very wrong.
Yes, there is an AI element to the series, but it’s done incredibly well and it’s about so much more than that. Kat is such a well-written character, so believably human and incredibly relatable. Heck, I even love (love to hate or hate to love?) Lock.
Body of Lies features DCS Kat Frank and her holographic assistant AIDE Lock as they investigate the murder of a local MP. At the scene, they uncover a hidden message that seems to be targeting them. The series feels timely and resonant, in real life earlier this year CrimeOwl AI launched to help investigators process thousands of files in minutes, making it easier to connect evidence, uncover hidden patterns and generate new leads. It’s no surprise that Callaghan pre-empted this in her novels, as she has a background as a senior strategist researching the future impact of AI on the workforce.
Throughout the series there has been ambiguity surrounding Lock. Is it possible for the AI to have its own alternative motives and do a Skynet? There’s a knife-edge uncertainty throughout and I loved the resulting tension.
As mentioned I won’t go into too much more of the plot to avoid spoilers. I will say that there was a part that gave me Fight Club vibes and that the ending was superb. What a ride this masterpiece series has been.
Thank you to Simon & Schuster for the proof copy.
May 13, 2026
Guys, I’m bereft and mind-blown all in equal measure. I have just finished Jo Callaghan’s Kat & Lock series with the final instalment ‘Body Of Lies’ and I am NOT OK. What I have just experienced is nothing short of masterful. I have experienced every range of human emotion throughout this series, but especially with this book, which serves as the finale to close out this fantastic series.
It’s hard to believe that I only joined the ranks of the CallaFANS fairly recently, but I have devoured four books now in less than a month and I have become so emotionally invested with Kat & Lock that it’s almost unhealthy at this point. This series is so exquisitely crafted and everything has been leading up to this point. I can’t say too much about this book without spoiling anything, so I’m trying to do my very best to review ‘Body Of Lies’ without revealing anything and it’s HARD! What I will say, however, is that it’s hard to build up a series and close it so that everybody is satisfied, but I think I can say with some confidence that people are going to be sad. Yes, but I think people are going to be really satisfied and mind-blown by this explosive finale to a much-loved series.
I am going to miss Kat & Lock so much. They have brought me so much joy. I had tears steaming down my face reading the last chapters and I just know that this is going to be a series that stays with me for a long time to come. What Jo has created with this series and these characters in particular is phenomenal, and I cannot wait to see what she writes next. ‘Body Of Lies’ is out next week and I want to say a huge thank you to Jo for kindly sending me an early copy for review.
PS: This was the hardest spoiler-free review I think I’ve ever had to write 🤣🤭
It’s hard to believe that I only joined the ranks of the CallaFANS fairly recently, but I have devoured four books now in less than a month and I have become so emotionally invested with Kat & Lock that it’s almost unhealthy at this point. This series is so exquisitely crafted and everything has been leading up to this point. I can’t say too much about this book without spoiling anything, so I’m trying to do my very best to review ‘Body Of Lies’ without revealing anything and it’s HARD! What I will say, however, is that it’s hard to build up a series and close it so that everybody is satisfied, but I think I can say with some confidence that people are going to be sad. Yes, but I think people are going to be really satisfied and mind-blown by this explosive finale to a much-loved series.
I am going to miss Kat & Lock so much. They have brought me so much joy. I had tears steaming down my face reading the last chapters and I just know that this is going to be a series that stays with me for a long time to come. What Jo has created with this series and these characters in particular is phenomenal, and I cannot wait to see what she writes next. ‘Body Of Lies’ is out next week and I want to say a huge thank you to Jo for kindly sending me an early copy for review.
PS: This was the hardest spoiler-free review I think I’ve ever had to write 🤣🤭
May 24, 2026
A rollercoaster of emotions to finish the last in the Kat and Lock series. What do I do with myself now that I read this one at such speed to want to know how it ends.
This is one of the best series ever written from start to finish. The portrayal of grief through to Lock being AI. I wondered from the off how much I'd enjoy it with AI being involved. It makes you see both sides and it's all about how you use something.
To give a slight but not spoiler Kat and Lock are both deserving of the hero title. By the end I'm hoping Kat is saying goodnight to all her past demons. She's such a human character to her AI partner such opposites and it just worked.
Kat even more human in this one struggling from the aftermath of the book before. Kat will forever have a place in my heart from these books one incredible woman. Read for yourself you will not be disappointed. 500 stars if I could give.
This is one of the best series ever written from start to finish. The portrayal of grief through to Lock being AI. I wondered from the off how much I'd enjoy it with AI being involved. It makes you see both sides and it's all about how you use something.
To give a slight but not spoiler Kat and Lock are both deserving of the hero title. By the end I'm hoping Kat is saying goodnight to all her past demons. She's such a human character to her AI partner such opposites and it just worked.
Kat even more human in this one struggling from the aftermath of the book before. Kat will forever have a place in my heart from these books one incredible woman. Read for yourself you will not be disappointed. 500 stars if I could give.
June 2, 2026
Wow! What a final book! I’ve absolutely loved the series and the last book did not disappoint!
Absolutely fantastic writing as well as being ‘on topic’ and interesting too.
AI is definitely here, whether we embrace it or not…
Absolutely fantastic writing as well as being ‘on topic’ and interesting too.
AI is definitely here, whether we embrace it or not…
July 5, 2026
This is a great series, highly recommend.
May 30, 2026
Just bloody brilliant! So sad this is the last in this series of 4 books. I have really loved each book.
June 12, 2026
This is the final book in a great series. There's more politics and arguments for and against AI in this one, which I got a bit fed up with towards the end.
Review of advance copy
Book Review 📚
Body of Lies - Jo Callaghan
Rating 5 Stars ! ⭐️⭐️⭐️⭐️⭐️
First of all thank you to bestie Michaela for very kindly providing me with a copy of this proof because it made my whole year 🙏🤣
However this book, where do I even begin ?! It was never going to be less than five stars so let's get that bit out of the way, absolutely amazing 👏
We follow Kat, Lock and the rest of the team whilst they are trying to solve the murder of a local MP which occurs on the night of Halloween, also during a power cut. I'm not going to say anymore about the plot as I obviously don't want to spoil anything !
I am sad that the series has come to an end as I love every single one of the characters so much and that just shows how amazing Jo writes ! However I will say believe it's been concluded fabulously and I wouldn't have wanted it any other way.
I don't know what to do now it's all over, I guess when the audiobook is released later this year I'll just have to do a re-read of the whole series ?! 💁♀️
Body of Lies - Jo Callaghan
Rating 5 Stars ! ⭐️⭐️⭐️⭐️⭐️
First of all thank you to bestie Michaela for very kindly providing me with a copy of this proof because it made my whole year 🙏🤣
However this book, where do I even begin ?! It was never going to be less than five stars so let's get that bit out of the way, absolutely amazing 👏
We follow Kat, Lock and the rest of the team whilst they are trying to solve the murder of a local MP which occurs on the night of Halloween, also during a power cut. I'm not going to say anymore about the plot as I obviously don't want to spoil anything !
I am sad that the series has come to an end as I love every single one of the characters so much and that just shows how amazing Jo writes ! However I will say believe it's been concluded fabulously and I wouldn't have wanted it any other way.
I don't know what to do now it's all over, I guess when the audiobook is released later this year I'll just have to do a re-read of the whole series ?! 💁♀️
May 28, 2026
I really enjoyed this series overall, but this was definitely my least favourite of the four. The ending felt quite underwhelming to me, and I didn’t really enjoy the “twist” it just didn’t feel aligned with everything built up in the previous books. It felt like the author was aiming for shock factor, but unfortunately it fell a bit flat for me and I wasn’t overly fussed with the overall arching storyline for this book.
That said, I still really enjoyed the book as a whole and loved the series overall. Sadly, like a lot of series, it just lost a bit of momentum towards the end for me.
I’d rate this book 3.5 stars ⭐️
The overall series’s 4.5 ⭐️
That said, I still really enjoyed the book as a whole and loved the series overall. Sadly, like a lot of series, it just lost a bit of momentum towards the end for me.
I’d rate this book 3.5 stars ⭐️
The overall series’s 4.5 ⭐️
July 10, 2026
5.0 / 5.0
Absolutely devastated that this is the last book of the series, but I understand why it is and why it had to happen. Callaghan even made me read the acknowledgments for the first time in any book. I always wondered what would happen in this series, when I first started the series I always asked myself - how would this end? Because at the start, there really is no end is there, the timing of the book and rise of AI to this current year/ day and age. I understand it and get it, the ending was pulling on my heart strings. Truly a well written book from start to finish, the twist really did get me and it all makes sense. I can’t fault Callaghan for ending this series, because thats the whole point isn’t it? You can’t end AI, you can stop what we’ve started, and it asks the bigger question for the future - what happens when machines start to develop a consciousness. To avoid straying away too far, seriously if you haven’t done so already - please grab the first book and read it. Finish the series. It’s probably one of the most unique series that’s I’ve read ever.
The book begins with DCS Kat Frank who returns to work after the events of the previous book (which is spoilt if you haven’t read it in the last book), only to find she’s straight into another high profile case. On the night of Halloween, a local MP is found murdered with a taunting message written in binary code target to Kat “catch me if you can”. The victim’s anti- AI sentiments suggest a political motive, which she investigates with her partner AIDE Lock - but when a cyber attack takes out the national grid Kat and lock have to race against the clock to track down the hacker before thousands die. Tangled in a web of suspicion and lies- Kat must chose who and what to believe when the trust seems to defy both instinct and logic.
Truly phenomenal book, but you won’t get the impact of eveyrones decisions if it’s the first time reading this book, Kat’s relationship and dynamic with AIDE Lock, the team dynamic after the events of the previous book. If you truly want to experience the journey please start from the beginning. A wonderful book, series - thank you Callaghan for such a great, thought provoking book.
Absolutely devastated that this is the last book of the series, but I understand why it is and why it had to happen. Callaghan even made me read the acknowledgments for the first time in any book. I always wondered what would happen in this series, when I first started the series I always asked myself - how would this end? Because at the start, there really is no end is there, the timing of the book and rise of AI to this current year/ day and age. I understand it and get it, the ending was pulling on my heart strings. Truly a well written book from start to finish, the twist really did get me and it all makes sense. I can’t fault Callaghan for ending this series, because thats the whole point isn’t it? You can’t end AI, you can stop what we’ve started, and it asks the bigger question for the future - what happens when machines start to develop a consciousness. To avoid straying away too far, seriously if you haven’t done so already - please grab the first book and read it. Finish the series. It’s probably one of the most unique series that’s I’ve read ever.
The book begins with DCS Kat Frank who returns to work after the events of the previous book (which is spoilt if you haven’t read it in the last book), only to find she’s straight into another high profile case. On the night of Halloween, a local MP is found murdered with a taunting message written in binary code target to Kat “catch me if you can”. The victim’s anti- AI sentiments suggest a political motive, which she investigates with her partner AIDE Lock - but when a cyber attack takes out the national grid Kat and lock have to race against the clock to track down the hacker before thousands die. Tangled in a web of suspicion and lies- Kat must chose who and what to believe when the trust seems to defy both instinct and logic.
Truly phenomenal book, but you won’t get the impact of eveyrones decisions if it’s the first time reading this book, Kat’s relationship and dynamic with AIDE Lock, the team dynamic after the events of the previous book. If you truly want to experience the journey please start from the beginning. A wonderful book, series - thank you Callaghan for such a great, thought provoking book.
June 6, 2026
This is the last book in the Kat and Lock series and OH MY!! This is packed with so much drama the plot twist was SOMETHING ELSE! When a local MP is murdered, it is down to Kat and Lock to try and figure it all out! However, this takes one sinister turn! I have to admit, the ending was everything in this book, to the point that I felt sad it was coming to an end! I didn’t expect it to end the way it did but it certainly felt fitting! I would definitely recommend the whole series (now available on KU!) but it will change your view on AI! Add this to your TBR immediately! I am going back to stare at my wall now!
May 21, 2026
Wow. Just wow!
This is such a brilliant series and this final instalment from Jo Callaghan meets and exceeds all expectations.
It’s a bitter sweet moment to read the final
chapter and I’ve loved being back in the world with Kat and Lock.
Tense and captivating, Jo Callaghan has again written a wonderful story- full of suspense and drama- we’re taken on a thrill ride adventure as Kat needs to decide on gut instinct or logic again.
This is one series I recommend again and again. Jo’s writing is detailed and gives a fascinating insight to the possibilities of the future.
This is such a brilliant series and this final instalment from Jo Callaghan meets and exceeds all expectations.
It’s a bitter sweet moment to read the final
chapter and I’ve loved being back in the world with Kat and Lock.
Tense and captivating, Jo Callaghan has again written a wonderful story- full of suspense and drama- we’re taken on a thrill ride adventure as Kat needs to decide on gut instinct or logic again.
This is one series I recommend again and again. Jo’s writing is detailed and gives a fascinating insight to the possibilities of the future.
June 19, 2026
Wow! What an end to this fabulous series!
May 28, 2026
What a finale!!!
July 6, 2026
Great series of books, agree with others in that I found this one the most unbelievable and unrealistic which was a shame.
June 12, 2026
Time taken to read - 4 days
Pages - 448
Publisher -
Source - Bought
Blurb from Goodreads
The brand-new thriller featuring DCS Kat Frank and AIDE Lock from the award-winning and Sunday Times bestselling author of In the Blink of an Eye .
Human suspicion. AI manipulation.
Who can you trust when truth has no meaning?
DCS Kat Frank returns to work at the Future Policing Unit after a tragic loss, only to find herself thrust into a new high-profile case. On the night of Halloween a local MP is found murdered, with a taunting message written in binary code that seems to target Kat Catch me if you can.
The victim’s anti-AI sentiments suggest a political motive, and as Kat investigates with her partner AIDE Lock – the world’s first AI detective – she finds herself once again battling her own prejudices about the technological future he represents. But when a cyberattack takes out the National Grid, Kat and Lock have to race against the clock to track down the hacker before thousands die.
Tangled in a web of suspicion and deception, Kat must choose who and what to believe when the truth seems to defy both instinct and logic.
Can she set aside her old doubts and put her faith in her AI partner one last time?
Or will this case send Lock down a path she just can’t follow – a path that will leave humanity behind for good?
My Review
Book four and the final book in the series, I am gutted, I wanted more! I often say you can pick up a book and just start reading but I would say to go and read the previous ones so you get the full story/impact/connection. I think from the previous book I was kinda looking a bit side eye at Lock, this book I was a bit all over the place.
A politician is found dead, publicly posed, well known for being against AI and keep in mind Kat has come around a fair bit to Lock but still has issues and reserves about AI. When a cyber attack hits and those in charge are held to ransom, realising just how heavily reliable we have become on technology and AI. Lives, thousands of innocent lives hang in the balance but the powers that be do not ever negotiate with terrorists do they?
This one had me suspicious and as Kat got more suspicious so did I but then I am totally murder she wrote with most crime fiction and side eye everyone lol. This one has threat to life especially featuring young/vulnerable in society, investigation of the murder of a outspoken MP plus the clock counting down quick to a shocking threat if demands aren't met. Gutted this is the last book but think the author done well to keep us interested for the four books and question AI use, grief, love, friendship, integrity, police work and family!
Pages - 448
Publisher -
Source - Bought
Blurb from Goodreads
The brand-new thriller featuring DCS Kat Frank and AIDE Lock from the award-winning and Sunday Times bestselling author of In the Blink of an Eye .
Human suspicion. AI manipulation.
Who can you trust when truth has no meaning?
DCS Kat Frank returns to work at the Future Policing Unit after a tragic loss, only to find herself thrust into a new high-profile case. On the night of Halloween a local MP is found murdered, with a taunting message written in binary code that seems to target Kat Catch me if you can.
The victim’s anti-AI sentiments suggest a political motive, and as Kat investigates with her partner AIDE Lock – the world’s first AI detective – she finds herself once again battling her own prejudices about the technological future he represents. But when a cyberattack takes out the National Grid, Kat and Lock have to race against the clock to track down the hacker before thousands die.
Tangled in a web of suspicion and deception, Kat must choose who and what to believe when the truth seems to defy both instinct and logic.
Can she set aside her old doubts and put her faith in her AI partner one last time?
Or will this case send Lock down a path she just can’t follow – a path that will leave humanity behind for good?
My Review
Book four and the final book in the series, I am gutted, I wanted more! I often say you can pick up a book and just start reading but I would say to go and read the previous ones so you get the full story/impact/connection. I think from the previous book I was kinda looking a bit side eye at Lock, this book I was a bit all over the place.
A politician is found dead, publicly posed, well known for being against AI and keep in mind Kat has come around a fair bit to Lock but still has issues and reserves about AI. When a cyber attack hits and those in charge are held to ransom, realising just how heavily reliable we have become on technology and AI. Lives, thousands of innocent lives hang in the balance but the powers that be do not ever negotiate with terrorists do they?
This one had me suspicious and as Kat got more suspicious so did I but then I am totally murder she wrote with most crime fiction and side eye everyone lol. This one has threat to life especially featuring young/vulnerable in society, investigation of the murder of a outspoken MP plus the clock counting down quick to a shocking threat if demands aren't met. Gutted this is the last book but think the author done well to keep us interested for the four books and question AI use, grief, love, friendship, integrity, police work and family!
June 22, 2026
So I am one of those readers who have read this series as it came along, starting with book one and hugely anticipating every new publications. I love the humanity and strength of DCS Kat Franks and Aide Locke has made me smile more than I can count. Their partnership has not only made for great reading but also often made the reader the pause and ask a number of questions, like: what does it mean to be human? Could AI ever work well and efficiently with humans, with the allocation of jobs between the two of them being optimised? Are there things an AI could miss despite it and human see? And many more, which you could probably think up yourself just thinking about development of AI in many different fields in the real world.
When Jo announced that this book would be the final one in this series I was both gutted (as I will miss this duo so much) and eager to find out how it would all end.
Body of Lies starts after the devastating loss we witnessed at the end of the previous book and the uncertainties and mistrust that created. Kat is still hugely struggling with the trauma she endured, so when a local MP is found murdered with a taunting message in binary code, she feels it is aimed directly at her and Locke. The victim argued against AI and the motive looks political but before long, the hunt for the killer turns hugely dangerous. Whoever is orchestrating this is extremely well organised and difficult to trace. When things take an even more sinister turn with a cyberattack taking down the National Grid, the police genuinely have a race against time on their hands before many more will die.
This was a superb finale and I loved everything about this book. If you’ve read the other three books, you’ll love this one and if you haven’t, don’t hesitate and please dive into this series! It’s so good!
When Jo announced that this book would be the final one in this series I was both gutted (as I will miss this duo so much) and eager to find out how it would all end.
Body of Lies starts after the devastating loss we witnessed at the end of the previous book and the uncertainties and mistrust that created. Kat is still hugely struggling with the trauma she endured, so when a local MP is found murdered with a taunting message in binary code, she feels it is aimed directly at her and Locke. The victim argued against AI and the motive looks political but before long, the hunt for the killer turns hugely dangerous. Whoever is orchestrating this is extremely well organised and difficult to trace. When things take an even more sinister turn with a cyberattack taking down the National Grid, the police genuinely have a race against time on their hands before many more will die.
This was a superb finale and I loved everything about this book. If you’ve read the other three books, you’ll love this one and if you haven’t, don’t hesitate and please dive into this series! It’s so good!
June 3, 2026
I recently reviewed a Lovejoy omnibus, bemoaning the fact that in a world of boilerplate crime novels we rarely get books like those that are genuinely different. Thanks to the AI detective Lock in this series, Jo Callaghan is a shining example of thinking differently - (not 'different', Apple) and it works brilliantly.
In the fourth and last of the series, Detective Superintendent Kat Frank and Lock take on what initially seems to be the political murder of an MP, but turns out to be a far bigger threat to the whole country. With neatly managed jeopardy it also puts a regular character's child at risk.
The book feels different to the first three, because of this large scale expansion of the case to take in the likes of the Home Secretary, Prime Minister and head of the Met. As such, the police procedural aspect of the storyline is a lot less to the fore as the plot develops. Instead we become engaged in a debate on how and when to use AI, what we can trust and what we can't, and the implications of adding robotic bodies to AIs. What's clever is that Callaghan manages to do this without ever losing her grip on the story or descending into tedious polemic.
As has always been the case there are some technical impossibilities here - in my review of the first book in the series, In the Blink of an Eye, which I classified as science fiction, I majored on these, particularly the problems of projecting a 3D hologram onto empty space. But taking more of a crime viewpoint, the issues are less significant, though I raised an eyebrow at Lock offering to power someone TV by remotely projecting electricity from the bracelet that projects his image to it (magic projection aside, if we had batteries that fit in a bracelet that could power a TV for hours, electric cars would benefit). But it's a minor quibble.
This is a worthy finale to the series, and I hope to see something new and equally different from Callaghan next.
In the fourth and last of the series, Detective Superintendent Kat Frank and Lock take on what initially seems to be the political murder of an MP, but turns out to be a far bigger threat to the whole country. With neatly managed jeopardy it also puts a regular character's child at risk.
The book feels different to the first three, because of this large scale expansion of the case to take in the likes of the Home Secretary, Prime Minister and head of the Met. As such, the police procedural aspect of the storyline is a lot less to the fore as the plot develops. Instead we become engaged in a debate on how and when to use AI, what we can trust and what we can't, and the implications of adding robotic bodies to AIs. What's clever is that Callaghan manages to do this without ever losing her grip on the story or descending into tedious polemic.
As has always been the case there are some technical impossibilities here - in my review of the first book in the series, In the Blink of an Eye, which I classified as science fiction, I majored on these, particularly the problems of projecting a 3D hologram onto empty space. But taking more of a crime viewpoint, the issues are less significant, though I raised an eyebrow at Lock offering to power someone TV by remotely projecting electricity from the bracelet that projects his image to it (magic projection aside, if we had batteries that fit in a bracelet that could power a TV for hours, electric cars would benefit). But it's a minor quibble.
This is a worthy finale to the series, and I hope to see something new and equally different from Callaghan next.
June 4, 2026
Body of Lies is the fourth and final book in the Kat and Lock series by Jo Callaghan, and Jo has steered this series towards a fantastic and gripping finale. It has been fascinating seeing Kat’s relationship with her AI assistant, Lock, grow over the course of this series. At first, Kat was resentful toward him, but now there is mutual respect between them and Kat really considers Lock as a friend.
The novel opens with the shocking murder of an MP who has vehemently opposed the use of AI and has campaigned against it. Following the murder, Kat finds herself in the killer’s sights. Following the murder, there is a lot of high-running tensions amongst the general public against AI, which makes things incredibly stressful and tense for Kat. But she is certainly not about to shy away from her job.
It is fascinating, if a little scary at times, to see how Lock’s own character has developed. He is an AI machine, so, effectively, he shouldn’t change at all, but he increasingly desires a physical body, and his own empathy does seem to be growing. There are times, of course, when Kat has to take over from Lock, particularly as he will explain everything bluntly and factually to people who are in a high state of stress. I did also genuinely feel for Lock in this book as he is desperate to get a body of his own.
Jo Callaghan paints a very scary picture of what could happen if AI continues to grow, as it is doing at the moment. She does this in a very tense way towards the end of the book, and I thought this upped the pace and tension very well. It certainly took a direction I didn’t expect the book to take. I think AI is a technology where, although it can be very useful, we have to be incredibly careful with it.
Body of Lies is a very satisfactory end to a brilliant series that I have thoroughly enjoyed.
The novel opens with the shocking murder of an MP who has vehemently opposed the use of AI and has campaigned against it. Following the murder, Kat finds herself in the killer’s sights. Following the murder, there is a lot of high-running tensions amongst the general public against AI, which makes things incredibly stressful and tense for Kat. But she is certainly not about to shy away from her job.
It is fascinating, if a little scary at times, to see how Lock’s own character has developed. He is an AI machine, so, effectively, he shouldn’t change at all, but he increasingly desires a physical body, and his own empathy does seem to be growing. There are times, of course, when Kat has to take over from Lock, particularly as he will explain everything bluntly and factually to people who are in a high state of stress. I did also genuinely feel for Lock in this book as he is desperate to get a body of his own.
Jo Callaghan paints a very scary picture of what could happen if AI continues to grow, as it is doing at the moment. She does this in a very tense way towards the end of the book, and I thought this upped the pace and tension very well. It certainly took a direction I didn’t expect the book to take. I think AI is a technology where, although it can be very useful, we have to be incredibly careful with it.
Body of Lies is a very satisfactory end to a brilliant series that I have thoroughly enjoyed.
May 31, 2026
What a rollercoaster of a series this has been, I've loved every book and the characters in them - they live rent free in my head - and to have this ending, wow I'm still trying to process. The range of emotions I've been through has quite frankly been epic and I’m going to need to lie down now!!
The characters are so strong and well written, their relationships and dynamics are human and flawed and the perfect juxtaposition to the logic of Lock. The story was fast paced and had my heart pounding, as Kat climbed those stairs my heart was in my mouth and the reveal, oh my that reveal was perfect. I cried at this book and I can't believe that it's over, although I will grab the audio to listen to just as I have with the previous ones as the narrator is amazing and it gives me a chance to immerse myself in the stories once more.
I can't recommend this series strongly enough - read, listen or immersive read but just pick this series up, you will not regret it!!!
*Police procedural
*Human Detective and AI partner
*Cutting edge technology
*Ethics
*Fast paced
The characters are so strong and well written, their relationships and dynamics are human and flawed and the perfect juxtaposition to the logic of Lock. The story was fast paced and had my heart pounding, as Kat climbed those stairs my heart was in my mouth and the reveal, oh my that reveal was perfect. I cried at this book and I can't believe that it's over, although I will grab the audio to listen to just as I have with the previous ones as the narrator is amazing and it gives me a chance to immerse myself in the stories once more.
I can't recommend this series strongly enough - read, listen or immersive read but just pick this series up, you will not regret it!!!
*Police procedural
*Human Detective and AI partner
*Cutting edge technology
*Ethics
*Fast paced
May 22, 2026
I've just finished this book and feel like I need to just sit and stare at the wall for a while. I used to think people were being dramatic saying stuff like that until I read this.
The whole series has been amazing. No blurb from me this time cos I think you genuinely need to read the whole series to appreciate what a masterpiece this book, book 4 in the series is.
With AI being a hot topic right now, splitting peoples views, this book is ahead of its game and I have loved how the plot has metaphorically grew legs over the series. I thought Jo couldn't get any better after Human Remains but this just blew it out of the water for me.
It's a fantastic read, it's gripping, tense and emotional and I can't really say anymore without giving anything away.
All the stars for this one 😍
5 ⭐️⭐️⭐️⭐️⭐️
The whole series has been amazing. No blurb from me this time cos I think you genuinely need to read the whole series to appreciate what a masterpiece this book, book 4 in the series is.
With AI being a hot topic right now, splitting peoples views, this book is ahead of its game and I have loved how the plot has metaphorically grew legs over the series. I thought Jo couldn't get any better after Human Remains but this just blew it out of the water for me.
It's a fantastic read, it's gripping, tense and emotional and I can't really say anymore without giving anything away.
All the stars for this one 😍
5 ⭐️⭐️⭐️⭐️⭐️
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