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Kat and Lock #4
Body of Lies
Not yet published
Expected 21 May 26The 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?
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
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?
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
- GenresThriller
Kindle Edition
Expected publication May 21, 2026
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Displaying 1 - 12 of 12 reviews
January 15, 2026
What a way to end the series!
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.
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 ?! 💁♀️
Review of advance copy received from Publisher
⭐️ 5 ⭐️
Loved it!
Review to follow.
Loved it!
Review to follow.
January 11, 2026
Was it my age, the raging hormones, or just how well written this book is, how heavily the ending lands, that had me in tears? I suspect somewhere in a mix of all three but I warn you now. If you are a fan of the books, if you have any love for Kat and her most unusual of partners in crime fighting, Lock, then do not underestimate how much reading this book is going to hurt, becuase it is. So, so sad that this is the final book, but if the series has to end, what a way to go.
I have out off writing a review of this book, not because I didn't enjoy it, because I absolutely, categorically did. It is simply because I don;t know if I have the words to do it justice when all I want to do is shout about all the "whaaaaat?", "OMG!" and "what the heck did you just do" that really do fall into spoiler territory. I can't and I won't just still. All of those and more. If you thought the ending of the previous book was shocking, just you wait. This book. So topical, so powerful. So absolutely brilliant.
I really am trying to avoid spoilers so this will be necessarily vague. Needless to say, we find Kat still reeling from what happened in the Human Remains, and trying to come to terms with what she believed she heard and saw in those dying pages. It's a big deal, as is moving back into her home for the first time since that fateful day that changed everything. I like how the author has portrayed this really clear emotional struggle that Kat goes through, wanting to rely on Lock but fearful of what has passed and what might come to be. It's not long before she has a very welcome distraction though in the form of the discovery of a body in her own home town, that of someone very critical of evolving AI capabilities and especially their place in the Police force. Not really hard to guess how quickly this is linked back to Kat and Lock or even how quickly this could all well go south ...
Which, ironically, it does. To Westminster and series of events that really do form the heart of this book. And that is where my recap ends and you have to read the book to get the rest for yourself. Whilst the murder investigation is equal parts intriguing and frustrating, and the list of potential suspects both finite and wide reaching given the victims status in the community, it is in the scenes in the latter part of the book where the story really picks up pace. Where Jo Callaghan plays an absolute blinder. I was both suckered in and also sceptical. I wanted to believe in the characters I have come to love even as all the evidence pointed wholly against them. This is very much a ticking clock case with huge ramifications if Kat cannot solve it, and also one in which she is going to have to rely on her own wits in order to come good. There is tension and intensity in every scene, and I had so many thoughts, doubts even, swirling in my mind at one time that I couldn't have looked away or put the book down even if I wanted to. Which I did not.
This book is so topical, generating such important questions for discussion that it probably the kind of thing that should be on a school English Lit syllabus. I had barely finished reading when the whole topic of AI and whether or not it would ever be capable of conscious decision making was on the morning news. And with all the recent take of AI being abused for the purpose of abusing others, the ethical, as well as very real environmental concerns of using AI is not only something brought to the fore in this book, but something I am ever more conscious now in the real world. And that is a powerful thing to pull from a book that is exceedingly thought provoking entertainment.
The ending of the book is shocking, heartbreaking even. I nearly dislocated my jaw, it fell so fast. And then the tears - emotional not pain derived - that were almost inevitable from the very first page of the book. You know you are heading towards an ending when you start reading a 'last in the series', but I never expected it to be this hard hitting or poignant. I like the final touches of the book, care taken with her characters right to the very end, but by golly. I am going to miss this series, and, in the (sort of) words of Dorothy Gale, 'I think I'll miss you most of all, Lock'. A fitting, if sad finale and completely recommended.
I have out off writing a review of this book, not because I didn't enjoy it, because I absolutely, categorically did. It is simply because I don;t know if I have the words to do it justice when all I want to do is shout about all the "whaaaaat?", "OMG!" and "what the heck did you just do" that really do fall into spoiler territory. I can't and I won't just still. All of those and more. If you thought the ending of the previous book was shocking, just you wait. This book. So topical, so powerful. So absolutely brilliant.
I really am trying to avoid spoilers so this will be necessarily vague. Needless to say, we find Kat still reeling from what happened in the Human Remains, and trying to come to terms with what she believed she heard and saw in those dying pages. It's a big deal, as is moving back into her home for the first time since that fateful day that changed everything. I like how the author has portrayed this really clear emotional struggle that Kat goes through, wanting to rely on Lock but fearful of what has passed and what might come to be. It's not long before she has a very welcome distraction though in the form of the discovery of a body in her own home town, that of someone very critical of evolving AI capabilities and especially their place in the Police force. Not really hard to guess how quickly this is linked back to Kat and Lock or even how quickly this could all well go south ...
Which, ironically, it does. To Westminster and series of events that really do form the heart of this book. And that is where my recap ends and you have to read the book to get the rest for yourself. Whilst the murder investigation is equal parts intriguing and frustrating, and the list of potential suspects both finite and wide reaching given the victims status in the community, it is in the scenes in the latter part of the book where the story really picks up pace. Where Jo Callaghan plays an absolute blinder. I was both suckered in and also sceptical. I wanted to believe in the characters I have come to love even as all the evidence pointed wholly against them. This is very much a ticking clock case with huge ramifications if Kat cannot solve it, and also one in which she is going to have to rely on her own wits in order to come good. There is tension and intensity in every scene, and I had so many thoughts, doubts even, swirling in my mind at one time that I couldn't have looked away or put the book down even if I wanted to. Which I did not.
This book is so topical, generating such important questions for discussion that it probably the kind of thing that should be on a school English Lit syllabus. I had barely finished reading when the whole topic of AI and whether or not it would ever be capable of conscious decision making was on the morning news. And with all the recent take of AI being abused for the purpose of abusing others, the ethical, as well as very real environmental concerns of using AI is not only something brought to the fore in this book, but something I am ever more conscious now in the real world. And that is a powerful thing to pull from a book that is exceedingly thought provoking entertainment.
The ending of the book is shocking, heartbreaking even. I nearly dislocated my jaw, it fell so fast. And then the tears - emotional not pain derived - that were almost inevitable from the very first page of the book. You know you are heading towards an ending when you start reading a 'last in the series', but I never expected it to be this hard hitting or poignant. I like the final touches of the book, care taken with her characters right to the very end, but by golly. I am going to miss this series, and, in the (sort of) words of Dorothy Gale, 'I think I'll miss you most of all, Lock'. A fitting, if sad finale and completely recommended.
Review of advance copy received from Publisher
Thanks to Simon and Schuster for the gifted proof of this title in return for an honest review.
This is an epic conclusion to the series - which includes In the Blink of An Eye, Leave No Trace, and Human Remains - and whilst it is epic, the fact that it's the last one is just not good news, because this has been just one of the greatest series I've read. Whilst Jo has done a wonderful job in rounding everything up, I don't like the idea that there won't be another to look forward to.
Like I said with the previous books, Jo has an amazing capacity for writing about grief, which I imagine comes from her own bereavement. As someone who has lost a lot of people, I find it really difficult to explain just how I feel but she's taken the words straight from my heart and it's just beautiful.
I think it's a very timely book. Obviously the whole series is about AI, but this one looks into the safety of it, the job losses, and that is becoming a genuine fear, particularly in the creative industries, and so whilst it was a thoroughly enjoyable book, it is also thought-provoking.
Also this idea of an MP being killed. No matter what their policies, no-one deserves to be murdered, but sadly this is not solely found in fiction.
I found Lock was quite irritating in this one, for the most part (he does redeem himself as the book goes on). That's not a negative point, but rather a compliment to Jo's writing. We have seen this "man" go through four books and he has grown and learnt and is as close to human as AI can be, and with that comes new emotions, new reactions, new intelligence, and it's frightening.
Whilst the other books did focus on AI, obviously, it was more in relation to the crimes. Whereas this one looks at it on a more national and global scale, and looks at how much we rely on AI, robots, electricity, machines; we focus on how it can help and ignore how it can harm.
This is about more than "just" a murder; it has so many layers to it, feels more personal and more targeted.
It is rounded off nicely, everything tied up, but I still can't believe it's finished. I've spend the last few years excited for the next instalment, and now that's it. But it'll be interesting to see what avenue Jo goes down now.
This is an epic conclusion to the series - which includes In the Blink of An Eye, Leave No Trace, and Human Remains - and whilst it is epic, the fact that it's the last one is just not good news, because this has been just one of the greatest series I've read. Whilst Jo has done a wonderful job in rounding everything up, I don't like the idea that there won't be another to look forward to.
Like I said with the previous books, Jo has an amazing capacity for writing about grief, which I imagine comes from her own bereavement. As someone who has lost a lot of people, I find it really difficult to explain just how I feel but she's taken the words straight from my heart and it's just beautiful.
I think it's a very timely book. Obviously the whole series is about AI, but this one looks into the safety of it, the job losses, and that is becoming a genuine fear, particularly in the creative industries, and so whilst it was a thoroughly enjoyable book, it is also thought-provoking.
Also this idea of an MP being killed. No matter what their policies, no-one deserves to be murdered, but sadly this is not solely found in fiction.
I found Lock was quite irritating in this one, for the most part (he does redeem himself as the book goes on). That's not a negative point, but rather a compliment to Jo's writing. We have seen this "man" go through four books and he has grown and learnt and is as close to human as AI can be, and with that comes new emotions, new reactions, new intelligence, and it's frightening.
Whilst the other books did focus on AI, obviously, it was more in relation to the crimes. Whereas this one looks at it on a more national and global scale, and looks at how much we rely on AI, robots, electricity, machines; we focus on how it can help and ignore how it can harm.
This is about more than "just" a murder; it has so many layers to it, feels more personal and more targeted.
It is rounded off nicely, everything tied up, but I still can't believe it's finished. I've spend the last few years excited for the next instalment, and now that's it. But it'll be interesting to see what avenue Jo goes down now.
Review of advance copy received from Publisher
Body of Lies is the perfect finale to what has been a truly exceptional series. It’s fair to say that the DCS Kat Frank and AIDE Lock novels are my all time favourite series and with book 3 finishing on a huge cliff-hanger, I couldn’t wait to find out how it was all going to end!
I’m not going to tell you anything about the plot - I went into it knowing nothing and I think that’s the best way. At this point if you haven’t read books 1 to 3 then go back and read them first, this is a series you definitely want to read in order to get the most out of it.
If I was to try and sum this book up I’d say it was poignant, funny, thrilling, exciting, terrifying, shocking but ultimately so moving and human. It gave me everything I wanted and so much more. The twists and turns were exquisitely plotted with references back to earlier books that just reinforced for me how much of a genius Jo is!
I did not see the ending coming, yet it made perfect sense once all had been revealed - always the sign of a truly great book in my opinion. And as is customary in this series there’s one final moment to leave you staring at the wall open-mouthed!
Jo really struck gold with the inclusion of AI in a police procedural when she came up with this series but it’s her knowledge, skill and sheer brilliance that have made it such a special set of books. They really are an example of how fiction novels can broaden your mind, your understanding, and your empathy - if only the humans will listen.
I’m not going to tell you anything about the plot - I went into it knowing nothing and I think that’s the best way. At this point if you haven’t read books 1 to 3 then go back and read them first, this is a series you definitely want to read in order to get the most out of it.
If I was to try and sum this book up I’d say it was poignant, funny, thrilling, exciting, terrifying, shocking but ultimately so moving and human. It gave me everything I wanted and so much more. The twists and turns were exquisitely plotted with references back to earlier books that just reinforced for me how much of a genius Jo is!
I did not see the ending coming, yet it made perfect sense once all had been revealed - always the sign of a truly great book in my opinion. And as is customary in this series there’s one final moment to leave you staring at the wall open-mouthed!
Jo really struck gold with the inclusion of AI in a police procedural when she came up with this series but it’s her knowledge, skill and sheer brilliance that have made it such a special set of books. They really are an example of how fiction novels can broaden your mind, your understanding, and your empathy - if only the humans will listen.
Review of advance copy received from Author
Thank you so much for my gifted proof from Simon and Shuster. Farewell Kat and Lock in their final instalment! This series has been a firm favourite of mine. DCS Kat Frank has returned to the Future Policing Unit in Warwickshire after a terrible incident six months ago. I wanted to take my time reading this so I read a few chapters every day to make it last. After a body of MP is found murdered with a taunting message written in binary code that seems to target Kat and Lock "Catch me if you can". Can Kat and Lock solve this crime? Will they find the culprit? How does this tie in with Angela's views on AI and their proposed advances? The team must race to find answers amidst the chaos of a cyberattack that affects the National Grid! It was dark, disturbing, engrossing, fast paced, full of twists and turns, humorous in places, nail biting and above all tense and terrifying and unputdownable! The subject matter does make you think on how this AI technology can affect human lives and their work. I will miss you!
January 26, 2026
Synopsis——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 specifically: 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.
#mythoughts no spoilers! totally brilliant to be back with Kat and Lock. If you loved the other books in this series you will love this one you might shed a tear just saying ….
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 specifically: 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.
#mythoughts no spoilers! totally brilliant to be back with Kat and Lock. If you loved the other books in this series you will love this one you might shed a tear just saying ….
January 6, 2026
I had an early Christmas present last year - I feel very privileged to have received this advanced readers copy of AIDE Lock’s last book of the series!!!
Kat and Lock’s partnership grows stronger as the world goes into turmoil. A local MP is found murdered, and while the Future Policing Unit try to wrap their heads around the cause of death, a cyberattack takes out the National Grid. It’s a race against time to restore electricity before further catastrophes strike.
As always, Jo has delivered - this was outstanding, keeping me guessing throughout. It is great end to the series, although I am gutted it’s over.
The book is due for publication in May 2026. You DO NOT want to miss it!
Kat and Lock’s partnership grows stronger as the world goes into turmoil. A local MP is found murdered, and while the Future Policing Unit try to wrap their heads around the cause of death, a cyberattack takes out the National Grid. It’s a race against time to restore electricity before further catastrophes strike.
As always, Jo has delivered - this was outstanding, keeping me guessing throughout. It is great end to the series, although I am gutted it’s over.
The book is due for publication in May 2026. You DO NOT want to miss it!
Review of advance copy received from Publisher
I don’t use Goodreads anymore but had to come on and hype this book up.
My favourite thriller book series ever. I’m so sad it’s over but what an ending 👏🏼
My favourite thriller book series ever. I’m so sad it’s over but what an ending 👏🏼
Review of advance copy received from Publisher
I've throughly enjoyed this series and been a fan of Jo's writing since In the Blink of an Eye. Bereft it's over.
Thank you to Likely Suspects and Tandem publishers for this proof copy
Thank you to Likely Suspects and Tandem publishers for this proof copy
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