DS Rakesh Siyal is an idealist. Frustrated as an Edinburgh human rights lawyer, he joins the police, determined to solve the problems he sees with the criminal justice system from the inside, rather than out. His first day as a cop sees him sent down to Galashiels in the Scottish Borders, where he’s given a simple task – return a suspect to Glasgow to face justice.

In the shadow of the Pentland Hills, a man has been callously struck down in front of his home. Tyre marks suggest it was no accidental hit-and-run. Somebody wanted him dead and as the man fights for every breath, they might still get their wish. Grappling with the demons he thought he could leave behind after months away on enforced leave, D.S. Malkie McCulloch resists pressure from his superiors to pass the case on to the road policing unit, convinced that whoever was behind the wheel will be waiting for the chance to finish the job.

Was the biggest case of his career the worst mistake he ever made? Ten years ago, DCI Jack Logan stopped the serial child-killer dubbed "Mister Whisper", earning himself a commendation, a drinking problem, and a broken marriage in the process...When another child disappears a hundred miles north in the Highlands, Jack is sent to lead the investigation and bring the boy home. But as similarities between the two cases grow, could it be that Jack caught the wrong man all those years ago?

Detective Chief Inspector Harry Grimm is forced to take leave from Bristol’s Major Investigations Team when his boss, tired of Harry chasing the ghost of his murderous father, sends him north on secondment. Used to city life and high stress, Harry fears his life will now be spent handing out speeding tickets, finding lost sheep, and directing tourists. But when a local teenager runs away, Harry finds himself pulled into an investigation much worse than anyone could have ever expected.

When the chief suspect in the notorious "peekaboo cop killer" case blew himself up, almost taking lead investigator DCI Duncan Bone with him, the psychologically damaged detective thought his days on the force were over. But, when another PC is abducted and murdered in the same deranged peekaboo fashion, Bone is persuaded to return to lead the new investigation.