When she's not digging up bones or other ancient objects, Ruth Galloway lectures at the University of North Norfolk. She lives happily alone in a remote place called Saltmarsh overlooking the North Sea and, for company; she has her cats Flint and Sparky, and Radio 4. When a child's bones are found in the marshes near an ancient site that Ruth worked on ten years earlier, Ruth is asked to date them.

Brighton, 1950: When the body of a girl is found, cut into three, Detective Inspector Edgar Stephens is reminded of a magic trick: the Zig Zag Girl. The inventor of the trick, Max Mephisto, is an old friend of Edgar's. When the dead girl turns out to be known to him, Max decides to help Edgar investigate.

Clare Cassidy is no stranger to murder. A high school English teacher specializing in the Gothic writer R. M. Holland, she teaches a course on it every year. But when one of Clare’s colleagues and closest friends is found dead, with a line from R. M. Holland’s most famous story, “The Stranger”, left by her body, Clare is horrified to see her life collide with the story lines of her favorite literature. 

DS Caitlin Fitzgerald has a secret—but it's one she's deleted from her memory. In the 1990s when she was at school, she and her friends killed a fellow pupil. Thirty years later, Caitlin is happily married and loves her job as a police officer. One day, her husband persuades her to go to a school reunion and another ex-pupil, Garfield Rice, is found dead, supposedly from a drug overdose. As Garfield was an eminent Labour MP and the investigation is high profile, it's headed by Caitlin's new boss, DI Harbinder Kaur. 

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?

DI Nikki Galena: A police detective with nothing left to lose, she's seen a girl die in her arms, and her daughter will never leave the hospital again. She's gotten tough on the criminals she believes did this to her. Too tough. And now she's been given one final warning: make it work with her new sergeant, DS Joseph Easter, or she's out.

Three very different women come together at isolated Baikie’s Cottage on the North Pennines to complete an environmental survey. Rachael, the team leader, is still reeling after a double betrayal by her lover and boss, Peter Kemp. Anne, a botanist, sees the survey as a chance to indulge in a little deception of her own. And then there is Grace, a strange, uncommunicative young woman hiding plenty of her own secrets. 

Thirty years ago, a child was found in the New Jersey backwoods. He had been living a feral existence, with no memory of how he got there or even who he is. Everyone just calls him Wilde. Now a former soldier and security expert, he lives off the grid, shunned by the community - until they need him. A child has gone missing. With her family suspecting she’s just playing a disappearing game, nobody seems concerned except for criminal attorney Hester Crimstein. She contacts Wilde, asking him to use his unique skills to find the girl.

Discovered living a feral existence in the Ramapo mountains of New Jersey, he has grown up knowing nothing of his parents, and even less about his own identity. When a match on a DNA database puts him on the trail of a close relative, Wilde thinks he might be about to solve the mystery of who he really is. Only this relation disappears as quickly as he's resurfaced. Wilde continues his research, becoming caught up in a community committed to exposing anonymous online trolls. Then people start to die and it soon becomes clear that a serial killer is targeting this secret community.

'And in Edinburgh of all places. I mean, you never think of that sort of thing happening in Edinburgh, do you...?' 'That sort of thing' is the brutal abduction and murder of two young girls. And now a third is missing, presumably gone to the same sad end. Detective Sergeant John Rebus, smoking and drinking too much, his own young daughter spirited away south by his disenchanted wife, is one of many policemen hunting the killer.