From the author of In the Blink of an Eye, the Sunday Times bestseller, winner of the CWA ILP John Creasey (New Blood) Dagger and Theakston Old Peculier Crime Novel of the Year.

DCS Kat Frank and AIDE Lock are back in a cutting-edge new thriller.

The truth will always come out, but at what cost?

Fresh from successfully closing their first live case, the Future Policing Unit are called in to investigate when a headless, handless body is found on a Warwickshire farm. But as they work to identify the victim and their killer, the discovery of a second body begins to spark fears that The Aston Strangler is back. And as the stakes rise for the team, so do the tensions brewing within it.

When DCS Kat Frank is accused of putting the wrong man behind bars all those years ago, AIDE Lock – the world's first AI Detective – pursues the truth about what happened with relentless logic. But Kat is determined to keep the past buried, and when she becomes the target of a shadowy figure looking for revenge, Lock is torn between his evidence-based algorithms and the judgement of his partner, with explosive results.

When everything hangs in the balance, it will all come down to just how much an AI machine can learn, and what happens when they do . . .