Jack races to find former nemesis Ronan Meyers, who has been kidnapped and is being held for ransom. Jack supports Kate as she prepares for her operation, while Darragh comes into his own as Jack's assistant.

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.

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.

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.