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.

Seven months after his mother's stroke, and continuing on his path of sobriety and healthier living, Jack is called on to investigate the death of a female university student, who falls from a roof while dressed in theatre costume. A ring of paper around her wrist contains an apparent suicide note written in her blood, and Gardai assume the death to be drug related.

Jack investigates the death of a priest who has been beheaded, and discovers the cleric abused two boys several years earlier. As more secrets from the church are revealed, Jack drifts back into his old habits, and discovers more of his own demons, along with the horrendous consequences the victims of the priest's earlier abuse are still enduring.

Riddled with guilt after a personal tragedy, Jack leaves Galway for Dublin. There he meets Rosie, a young girl who witnessed her mother's murder, but has suppressed the memory. While also dealing with a travellers' feud, Jack must help Rosie to recall the events of her mother's death before the killer strikes again.