The Complaints: that's the name given to the Internal Affairs department who seek out dirty and compromised cops, the ones who've made deals with the devil. And sometimes The Complaints must travel. A major inquiry into a neighboring police force sees Malcolm Fox and his colleagues cast adrift, unsure of territory, protocol, or who they can trust. An entire station-house looks to have been compromised, but as Fox digs deeper, he finds the trail leads him back in time to the suicide of a prominent politician and activist.

Nobody likes The Complaints—they're the cops who investigate other cops. It's a department known within the force as The Dark Side, and it's where Malcolm Fox works. He's a serious man with a father in a nursing home and a sister who persists in an abusive relationship, frustrating problems about which he cannot seem to do anything.

The Rise is a gleaming residential tower, newly constructed from steel and blackened glass, that stands on some of London’s most prestigious real estate. Looming imposingly over Hyde Park, only multi-millionaires need apply for one of its sumptuous apartments. But when the young night concierge is found murdered in the building’s lobby, the elite residents quickly find their gilded lifestyles under unwelcome police scrutiny.

Oslo, 2018. Former long-distance runner Sonja Nordstrøm never shows at the launch of her controversial autobiography, Always Number One. When celebrity blogger Emma Ramm visits Nordstrøm’s home later that day, she finds the door unlocked and signs of a struggle inside. A bib with the number one has been pinned to the TV. Police officer Alexander Blix is appointed to head up the missing-persons investigation, but he still bears the emotional scars of a hostage situation 19 years earlier, when he killed the father of a five-year-old girl.

Sam Capra is living the life of his dreams. He's a brilliant young CIA agent, stationed in London. His wife Lucy is seven months pregnant with their first child. They have a wonderful home, and are deeply in love. They have everything they could hope for... until they lose it all in one horrifying moment.

The story opens with the apparently accidental drowning of a sixth form student in the Norfolk countryside. As a matter of routine, or so it seems, the case passes across the desk of Detective Sergeant Smith, recently returned to work after an internal investigation into another case that has led to tensions between officers at Kings Lake police headquarters. As an ex-DCI, Smith could have retired by now, and it is clear that some of his superiors wish that he would do so.

Half-Scottish, half-Italian Enzo MacLeod used to be one of the top forensics experts in Scotland, and now he lives in Toulouse, working as a university professor. Divorced in Scotland and widowed in France, he has an estranged Scottish daughter and a French daughter he has raised by himself. As if his life isn't complicated enough, he soon finds himself unexpectedly on the hunt for solutions to some vexing cold cases thanks to an ill-advised wager about the power of forensic science.

Albert Campion, an eccentric but intelligent and resourceful man, becomes involved in a mysterious crime in Black Dudley, an isolated country estate owned by the wealthy and secretive Dudley family. A grand gathering is taking place at the house, but not all will leave.

Ian Rutledge returns to his career at Scotland Yard after years fighting in the First World War. Unknown to his colleagues he is still suffering from shell shock, and is burdened with the guilt of having had executed a young soldier on the battlefield for refusing to fight. A jealous colleague has learned of his secret and has managed to have Rutledge assigned to a difficult case which could spell disaster for Rutledge whatever the outcome. A retired officer has been murdered, and Rutledge goes to investigate.

Northern Ireland, spring 1981. Hunger strikes, riots, power cuts, a homophobic serial killer with a penchant for opera, and a young woman’s suicide that may yet turn out to be murder: on the surface, the events are unconnected, but then things—and people—aren’t always what they seem. Detective Sergeant Duffy is the man tasked with trying to get to the bottom of it all. It’s no easy job—especially when it turns out that one of the victims was involved in the IRA but was last seen discussing business with someone from the loyalist Ulster Volunteer Force.

Met cop DI Rob Marshall is hot on the trail of the serial killer known as the Chameleon, who has abducted, tortured and killed a series of young women in Northwest London. As they close in, the Chameleon—who switches identity to get close to his victims—shoots Marshall’s partner and escapes.

Carl Mørck used to be one of Denmark’s best homicide detectives. Then a hail of bullets destroyed the lives of two fellow cops, and Carl - who didn’t draw his weapon - blames himself. So a promotion is the last thing he expects. But Department Q is a department of one, and Carl’s got only a stack of cold cases for company. His colleagues snicker, but Carl may have the last laugh, because one file keeps nagging at him: A liberal politician vanished five years earlier and is presumed dead. But she isn’t dead...yet.

Detective Sergeant Chris Waters got the call at 05.29 that July morning. This is it, said DCI Reeve, you'll be first there, it's all yours, you're the crime scene manager. Suddenly, after months of waiting and wondering, Waters finds himself in at the deep end, and alone at the scene of a puzzling murder. As the investigation proceeds, the detectives at Kings Lake Central find themselves visiting familiar places and talking to some familiar faces, while old enmities reappear in the incident room. Before this is over, Chris Waters will need to make a career-changing decision.

The daughter of a distinguished soldier, Bess Crawford follows in his patriotic footsteps, volunteering to serve her country as a nurse during the Great War. In 1916 she promises Lieutenant Arthur Graham that she will carry his dying request to a brother. When Bess arrives at the Graham house in Kent, Jonathan Graham listens to his brother's last wishes with surprising indifference.

Former soldier. Ex-copper. Current man on the edge. Shunned by his old colleagues, and dividing his time between a dead-end job and the bottom of a whisky bottle, former Police Scotland detective superintendent Bob Hoon’s life is a mess. Then an old face from Hoon’s Special Forces days turns up asking for help: His teenage daughter has been missing for months, the police have drawn a blank, and he needs the kind of help that only Hoon can provide. And besides, Hoon owes him one.