After a series of apparent suicides that have left four young women dead, a worried mother hires Taylor to find her missing 18-year-old daughter. But something about his new client makes the detective uneasy. While getting to the bottom of the earlier deaths, he discovers that the mother may have an ulterior motive for her search.

Determined to restore law and order, a group of local vigilantes known as the Pikemen is meting out its own brand of rough justice on the streets of Galway. Taylor comes face-to-face with the group during one of his investigations but soon ends up on the wrong side of the law himself.

Taylor is hired to look into past abuses at the infamous Magdalen laundries, the city's home for “wayward girls.” The daughter of a former inmate wants him to track down a woman called “Lucifer,” a particularly brutal nun who worked there. In the wake of two execution-style murders, Taylor realizes he's not alone in searching for Lucifer.

Against all odds, Jack Taylor is clean and sober. He worries about his mother, who has suffered a stroke and is living in a health care facility. But in his hometown Galway, grief is never far away.

When the dead body of an old priest, Father Royce, is discovered, beheaded, Father Malachy, of all people, asks Jack Taylor for help. Father Royce had abused two boys years earlier and Malachy was the only witness. ROYCE was moved overseas and the church covered up the crime - leaving the boys alone with their pain.

While wrapping up a small job on the outskirts of Dublin, Jack Taylor finds an itinerant girl, Rosie, seemingly running for her life, covered in blood. It transpires that the girl's mother, Sinead, had been murdered near a traveller's halting site. Sinead's husband is the main suspect. Jack is the only one who senses that Rosie is hiding something, that she saw more than she's letting on.

When a young man is found crucified, Jack investigates and uncovers a web of revenge and religious mania.

Jack must race against the clock to locate a former nemesis, Ronan Meyers, who has been kidnapped and held for ransom by a vigilante group called Headstone.

Jack is hired by the head of a software company to find out who has stolen valuable data, but when the main suspect is murdered Jack is convinced that his new employer is to blame.