Hidden away in an isolated cabin on the edge of her farm, seven-year-old Aisling Connolly shivers as the cold night air whistles through her thin jacket. It’s been two days since the men came, since her mammy told her to run like she’d never run before, to not look back. She hasn’t seen her parents since. And she’s terrified. But when Aisling is finally found by the police, she knows instinctively she can trust Detective Tessa Burns.

When a young boy discovers the body of a woman beneath a thick sheet of ice in a South London park, Detective Erika Foster is called in to lead the murder investigation. The victim, a beautiful young socialite, appeared to have the perfect life. Yet when Erika begins to dig deeper, she starts to connect the dots between the murder and the killings of three prostitutes, all found strangled, hands bound, and dumped in water around London.

Haunted by his inability to track down and save his missing wife, DCI Robert Kett leaves the Metropolitan Police behind and moves to Norwich with his three young children, hoping to heal their broken family. But his newfound peace doesn’t last. Two newspaper delivery girls have gone missing in the city, and the clues point to a serial kidnapper. Kett is dragged into the centre of one of the darkest cases of his career - a case that pits him head-to-head against a horrifying evil.

When a 15-year-old girl fails to make it home after school, DI Heather Filson believes she’s dealing with just another teenage runaway. The girl’s grandfather, a notorious Glasgow gangster, disagrees. Convinced one of his underworld enemies has grabbed her, he’s prepared to bathe the city in blood in order to bring his princess home.

Five years ago, DCI John Lomond led the search for notorious Glasgow child-killer ‘The Sandman', until personal tragedy forced him off the case. In Lomond's absence, the killer was never found. Now, with nothing but work left in his life, Lomond remains obsessed with the case–despite the nightmares it brings. When a child is abducted in similar Sandman fashion from an affluent Glasgow suburb, Lomond is brought in to find them before it's too late.