In the dim morning light, Orkney’s Skaill Bay is the backdrop for a calamity of nature’s making. When forensic scientist Rhona MacLeod joins the rescue efforts as a volunteer, she uncovers more than she bargained for: a human skeleton entombed in a stone crypt. The grave is believed to hail from the Viking Age, but Rhona's analysis of the content points to more recent and sinister evil. And a shadow is thrown over the investigation when the skeleton is finally identified, as unsettling connections between the victim and the very people trying to solve the case come to light.

As Acting DC Scott Cullen works with DC Craig Hunter to track down a witness who didn’t show during a court case, they stumble upon another crime–two homeless women, dying of a suspected heroin overdose. As they investigate, they uncover a far-reaching criminal empire, dealing death and misery to Edinburgh’s underclass. And come across another investigative team who may not be exactly on the same side. As the case brings two cops together and drives a wedge between another pair, can Cullen and Hunter rescue the witness and bring her assailant to justice?

On Christmas Eve, DCI Mackenzie Jones is called to a shooting at a remote farmhouse. Ralph Mallender believes his father lies dead inside. When three more bodies are discovered, it's clear a festive family gathering has turned into a gruesome tragedy. At first it seems like an open and shut case: a murder suicide committed by Ralph's volatile brother Cameron. Then new evidence makes Mack suspect the man who reported the crime is in fact the perpetrator. But Mack isn't the only one with a stake in the case.

It's DS Logan McRae's first day back on the job after a year off on the sick, and it couldn't get much worse. Three-year-old David Reid's body is discovered in a ditch: strangled, mutilated and a long time dead. And he's only the first. There's a serial killer stalking the Granite City, and the local media are baying for blood. Soon the dead are piling up in the morgue almost as fast as the snow on the streets, and Logan knows time is running out. More children are going missing. More are going to die.

DS George Cross can be rude, difficult and awkward with people. But his unfailing logic and dogged pursuit of the truth means his conviction rate is the best on the force. So when his police colleagues dismiss the death of a man as a squabble among Bristol's homeless community, Detective Sergeant George Cross is not convinced.