Book Review: Leave No Trace by Jo Callaghan
By Janet Webb
January 17, 2025
Leave No Trace and its predecessor, In the Blink of an Eye, are “inventive thrillers,” a description that barely encompasses the unusualness of Team Kat and Lock. Meet Detective Chief Superintendent Kat Frank of the Leek Wootton Police Department in Warwickshire, England. Leave No Trace opens with Kat verbally briefing her boss, Chief Constable McLeish, on the FPU (Future Policing Unit) that Kat leads. Sitting beside Kat is “AIDE Lock, her AI partner,” an Artificially Intelligent Detecting Entity. Lock is a hologram, and a detective. McLeish is an avowed skeptic of the program, “afraid they’d become a Trojan horse for yet more cuts to police numbers.” Kat, too, has some reservations about the efficacy of AI, but she learned, during the events of In the Blink of an Eye, to appreciate Lock’s specialized support.
But when she feared that her own son had become a victim in the case they were investigating over the summer, not one single other person had believed her: they’d assumed her emotions were clouding her judgement. Lock was the only one who’d agreed that the facts supported her hypothesis and had overridden its own protocols to help save her son. Kat still had reservations about the role of AI in policing, but although Lock’s algorithm-led approach could often be exasperating, she would never, ever forget how Lock alone had stood by her when she’d needed help the most.
Kat and Lock successfully closed the files on three cold cases, but Kat as reminds her boss, “what we can’t do is change the actual outcome.” To achieve a different outcome, it’s time to tackle live cases. Kat doesn’t falter under McLeish’s “unblinking glare,” and negativity, because since her husband died prematurely last year, the worst “had already happened” to her. Kat stands up for her team, saying DI Hassan (detective inspector) and DS Browne (detective sergeant) had “honed their policing skills,” and that ‘the speed with which Lock can analyse CCTV, social media and other data makes us one of the fastest and most effective teams I’ve ever worked with.’ Why not deploy Kat and her team on cases where they have a chance of favorably affecting the outcome? McLeish is resistant, especially since Lock, who has no filter, calls him out on his prejudices. Lock is a brilliant tactician and analyst, but he doesn’t understand the chain of command and “the nuances of human language and behaviour.” Balls to the wall, Kat is determined to have a go.
‘The whole point of the FPU is to develop a new model of policing for the future. We can’t do that unless we work on some live cases, sir.’
McLeish looked between Kat and the image of Lock sitting at his table. ‘It’s too risky.’
Who knows how McLeish would have come down if a case hadn’t come across his transom. He tells DCS Frank, ‘the body of a dead male has just been found crucified on top of Mount Judd, bollock-naked with his ears sliced off. You still up for a live case?’ Yes, sir, Chief Constable.
The man was crucified in the middle of the night—a snowy, cold evening that ordinarily would have been a perfect backdrop to the Christmas season. Kat and her team quickly establish the identity of the dead man, but they are unable to nail the killer. Another naked male, a man in the prime of life, is also found crucified. His eyes have been pecked out by crows circling in the air above a farmer’s field. Is this a war on men? Given that both dead men were seen for the last time in a bar, police issue a public warning to “local males aged between thirty and forty years old.”
- Avoid drinking in pubs
- If you must go to a pub, do not leave alone.
- Do not leave a pub with a stranger.
The warning concludes, “always let a friend know where you are.” Men are outraged—they’re being warned about going to the pub? They’re not having it. Women may find the police warnings to be nothing out of the ordinary: i.e., police putting the onus on women’s behavior to prevent a crime.
Leave No Trace is well-written and shockingly believable. The benefits/drawbacks of AI policing are shown in clear focus. For example, Lock can zip through thousands of camera shots of people entering a bar. What it/he can’t do as easily is meticulous, slow policing which involves looking at the reactions of the people in the bar to folks entering through the door. As it happens, both talents are needed to solve the case.
The second Kat and Lock police thriller “pits algorithms against experience, logic against instinct, and one undetectable killer against two extraordinary detectives.” It’s a compelling read and I’m looking forward to the third Kat and Lock.