View source for Leave No Trace by Jo Callaghan

{{infobox1
|title=Leave No Trace
|author=Jo Callaghan
|reviewer=Ruth Ng
|genre=Crime
|summary=A pacey, very readable detective story, with a sort of Chat GPT embodied in a hologram detective.  Yes, really!
|rating=4
|buy=Yes
|borrow=Yes
|pages=384
|publisher=Simon & Schuster UK
|date=March 2024
|isbn=9781398511200
|website=https://twitter.com/JoCallaghanKat
|video=cyLMscyjys4
|cover=139851120X
|aznuk=139851120X
|aznus=139851120X
}}

When a man is found crucified on the top of a hill in Nuneaton, DCS Kat Frank finds herself assigned to the case alongside her sidekick, the AI detective Lock.  It's their first live case together, having previously been very successful with several cold cases.  But when there is a second body found crucified a few days later, Kat is suddenly struggling with a potential serial killer and a very high profile case that draws a lot of unwanted attention to their AI Future Policing project.  Will they be able to solve the case in time, or will Kat find herself taken off the case and, potentially, out of a career?

With AI being the hot topic of the moment, this is a timely idea for a story.  It's the second part of  a series, but I came to this book without having read the first part and I found I settled into the story quickly.  Jo Callaghan gives an interesting look at what the not-too-distant future could look like technologically, and you get to see the very obvious advantages of an AI for the police.  Lock can very quickly sort and sift through huge amounts of data, finding profile matches, looking at social media, identifying suspects and victims, and assisting with autopsies.  But there are also the downfalls of those jobs being assigned to what is basically a computer that doesn't understand human emotions, reactions, responses and even conversational tone and the potential for some vital clue being missed because of that.  

Lock reminded me a little of Data from Star Trek, and there is the same sense through the story that Lock is learning and changing, and is perhaps struggling with the notion that he is only Artificial Intelligence.  I found it interesting that Lock is a hologram, as that's something quite different to having a detective robot as a sidekick.  I liked seeing the different ways Lock was used through the story, and actually I would have liked him to be in it a little bit more than he was.

I liked Kat as well.  She feels like a very natural character, and her personal situation gives a nuance to the story as she is still recovering from the death of her husband, and navigating through life alone now that her son is at University.  There are lots of strong women in positions of authority through the book, which is always good to see.  The story is also interesting in that it puts men in the position of risk, since it looks as if the killer is targeting men.  Reading some of the male responses to being told in the media that they should not go to the pub, and should stay at home and be careful, really made me laugh!  There were a couple of places where the social commentary was slightly jarring though, and I felt that perhaps a character didn't quite behave as I thought they should, or some comment was a little bit shoe-horned in.

The ending ramps up in pace, with one terrible situation piling onto another.  Whilst I enjoyed reading it, it did have a couple of slightly-too-convenient bits of tech suddenly being available to the team, which was a shame as I'd felt up until then that side of things had actually been very believable.  Still, I was racing through the pages and even with a couple of criticisms, this is a really good read with a nice mix of human interest and police procedure.  I'd definitely like to read more about Kat and Lock in the future.

You might also enjoy reading [[The Girl in the Spider's Web (Millennium Series) by David Lagercrantz]] or [[From Darkest Skies by Sam Peters]].

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