LEAVE NO TRACE

The second book in the British Midlands–set Kat and Lock series reteams what may be crime fiction’s oddest couple, given that one half of the pair isn’t even human.

A man has been found dead on Nuneaton’s Mount Judd, his nude body tied to a cross and his ears cut off. To identify the victim and solve the crime, the Warwickshire police force’s DCS Kat Frank once again partners with Artificially Intelligent Detecting Entity Lock, the world’s first AI detective, who takes the form of a 3-D holographic image of a 30-something Black man. According to Professor Adaiba Okonedo—the Black scientist who created Lock and whose personal experience with racism has left her wary of cops—the idea is to use bias-free AI to “rebuild public trust and confidence in policing.” Also good: In a matter of seconds, the AI detective can do things such as “cross-check the victim’s facial characteristics, height and weight with all social media posts matching white men between twenty-five and forty ­in the Nuneaton area.” To mystery readers not predisposed to reaching for tech thrillers, the premise may sound intimidatingly geeky, but once Callaghan establishes her terms, it’s one fleet, accessible scene after another. For the Star Trek savvy, conversations between Kat and her literal-minded partner may recall exchanges with Mr. Spock (Lock: “Your entire theory is built upon nothing but your imagination”; Kat: “It’s called empathy, Lock”). The novel’s central question—should humans fear replacement by machines?—hums throughout, but never hinders the story’s forward momentum, and the plot’s big reveal is unlikely to be foreseen by even the AI-abetted reader.

This thriller may feature state-of-the-art AI, but its solid craftsmanship is timeless.