In the summer of '69, the hard-living rockers of the British Invasion still rule London when former Rolling Stone Brian Jones is found floating in the pool of his palatial home. On a quiet residential block that should be far removed from the swinging party scene, Detective Sergeant Cathal Breen investigates the murder of a young woman. But the victim, known professionally as Julie Teenager, was a call girl for the rich and famous. As DS Breen hones in on his prime target, he receives a pointed warning: Watch your back. Fortunately, Breen doesn't have to work alone. His keenly intuitive, deeply moral partner Helen Tozer, despite the pregnancy that's interrupted her policing career, can't help being drawn into the case of a girl used and cast aside.

Sergeant Alexandra Cupidi, a recent transfer from the London metro police to the rugged Kentish countryside, faces a bizarre case: a woman found floating in local marsh land, dead of no apparent cause. The case gets even stranger when detectives contact the victim's next of kin, her son, a high-powered graphic designer living in London. Adopted at the age of two, he'd never known his mother until a homeless woman knocked on his door, claiming to be his mother, just the night before --- at the same time her body was being dredged from the water. Detective Cupidi must discover who the woman really was, who killed her, and how she managed to reconnect with her long lost son, apparently from beyond the grave.

A methodical, diligent and exceptionally bright detective, William South is an avid birdwatcher and trusted figure in his small town on the rugged Kentish coast. He also lives with the deeply buried secret that, as a child in Northern Ireland, he may have killed a man. When a fellow birdwatcher is found murdered in his remote home, South's world flips. The culprit seems to be a drifter from South's childhood; the victim was the only person connecting South to his early crime; and a troubled, vivacious new female sergeant has been relocated from London and assigned to work with South. As our hero investigates, he must work ever-harder to keep his own connections to the victim, and his past, a secret.

After being wounded in the line of duty, Detective Sergeant Breen recuperates on the family farm of his former partner, Helen Tozer. To fill the long and empty hours, he reviews the open case file for a murder that has haunted Helen for years: that of her younger sister. Breen discovers that the teenage victim had been having a secret affair with James Fletchet, the son of an affluent local landowner. Breen and Tozer return to London's Criminal Investigation Division, where their questions about Fletchet's past are met with resistance and suspicion.

Detective Sergeant Breen has a death threat in his inbox and a mutilated body on his hands. The dead man was the wayward son of a rising politician, and everywhere Breen turns to investigate, he finds himself obstructed and increasingly alienated. Breen begins to see that the abuse of power is at every level of society. And when his actions endanger those at the top, he becomes their target. Out in the cold, banished from a corrupt and fracturing system, Breen is finally forced to fight fire with fire.

Detective Sergeant Cathal Breen believes that the victim of a strangulation may be one of the many Beatles fans who regularly camp outside Abbey Road Studios. With his reputation tarnished by an inexplicable act of cowardice, this is Breen's last chance to prove he's up to the job. Both he and Helen Tozer, a young policewoman assisting him with the case, navigate a world where conservative tradition gives way to frightening new freedoms --- and troubling new crimes.