Maverick sleuth Declan Miller is back at work following the murder of his wife (and amateur ballroom dancing partner) Alex. Working with new partner and heavy metal enthusiast DS Sara Xiu, he is tasked with investigating the double killing of gangland family scion Adrian Cutler and IT consultant Barry Shepherd at the Sands Hotel. Initial evidence suggests a hired gun and a botched job. The search for the hitman begins and Miller begins to reconnect with his old network.

The targeted murder of four officers is only the first in a series of attacks that leaves police scared, angry, and, most disturbingly of all, vengeful. As Tom Thorne and Nicola Tanner dig into the reasons for the violence, a deeper darkness begins to emerge: the possibility that these murders are payback. The price paid for an unspeakable betrayal.

Ryan Wilkins grew up on a trailer park, a member of what many people would call the criminal classes. As a young Detective Inspector, he's lost none of his disgust with privileged elites - or his objectionable manners. But he notices things; they stick to his eyes. His professional partner, DI Ray Wilkins, of affluent Nigerian London heritage, is an impeccably groomed, smooth-talking graduate of Balliol College, Oxford. You wouldn't think they would get on. They don't. But when a young woman is found strangled at Barnabas Hall, they're forced to.

Every Monday evening six people gather in a smart North London house to talk about shame. A respected doctor, a well-heeled housewife, a young male prostitute...they could not be more different. All they have in common is a history of addiction. But when one of the group is murdered, it quickly becomes apparent that someone else in that circle is responsible. The investigation is hampered by the strict confidentiality that binds these individuals and their therapist together, which makes things difficult for Detective Inspector Nicola Tanner.

“Old spies grow ridiculous, River. Old spies aren’t much better than clowns.” Or so David Cartwright, the late retired head of MI5, used to tell his grandson. He forgot to add that old spies can be dangerous, too, especially if they’ve fallen on hard times—as River Cartwright is about to learn the hard way.

It is the early spring of 2016 and Queen Elizabeth is at Windsor Castle in advance of her 90th birthday celebrations. But the preparations are interrupted when a guest is found dead in one of the Castle bedrooms. The scene suggests the young Russian pianist strangled himself, but a badly tied knot leads MI5 to suspect foul play was involved. The Queen leaves the investigation to the professionals—until their suspicions point them in the wrong direction. Unhappy at the mishandling of the case and concerned for her staff's morale, the monarch decides to take matters into her own hands.

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.

On the backstreets of Lyon, France, an MI6 surveillance team are gunned down in a cold-blooded ambush. Thrust into the hunt for the assassin is the sole survivor – rookie covert operative Duncan Grant. His feats in training are already the stuff of legend. His tough, solitary existence on Scotland's Isle of Skye forging a man willing to kill to protect the innocent and save lives. But no training can prepare Grant for the devastating consequences his first kill will unleash.

One calm night in Twickenham, a businessman named Tom Treadnor is shot off his barstool at The Queen Pub. Superintendent Richard Jury is called in to investigate and quickly realizes that everyone in Treadnor’s life—from his widow, Alice, to the staff at his manor, to his business partner—had differing opinions of him. And to complicate things further, Jury has just happened upon a photo in a newspaper of a man in the United States, who is a dead ringer for Treadnor.

Three British couples meet around the pool on their Florida holiday and become fast friends. But on Easter Sunday, the last day of their vacation, tragedy strikes: the 14-year-old daughter of an American vacationer goes missing, and her body is later found floating in the mangroves. When the shocked couples return home to the UK, they remain in contact, and over the course of three increasingly fraught dinner parties they come to know one another better. But they don't always like what they find.

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.

DI Jan Talantire is called to a cottage in Ilfracombe, where the female occupant is found dead, impaled with a crucifix. The woman, who had been renting the house for a few months, is well known locally, but the documents at the house indicate her real name is Ruth Lyle. The name means nothing to the young PC who found her, DI Talantire knows this cannot be the body of Ruth Lyle.

Lachlan Kite is a member of BOX 88, an elite transatlantic black-ops outfit so covert that not even MI6 and the CIA are certain of its existence - but even the best spy can't anticipate every potential threat in a world where dangerous actors lurk around every corner. At the funeral of his childhood best friend, Lachlan falls into a trap that drops him into the hands of a potentially deadly interrogation, with his pregnant wife, also abducted, being held as collateral for the information he's sworn on his own life to protect.

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.

When a beautiful, wealthy student is found dead in her room in Oxford's most prestigious college, Detective Inspector Bridget Hart is called to investigate. The murdered girl appeared to have no enemies, yet was killed in a brutal and bloody assault. Haunted and driven by her own personal tragedy, newly promoted DI Bridget Hart has a lot to prove as she leads her first murder case. Her investigation uncovers a tangled web of lies, lust and ambition, and brings her into conflict with powerful interests.