After two pregnant women in Dingle who have never met each receive a chilling email warning them that they're in grave danger, the two decide to meet each other to figure out what is going on. But when one of the mothers, Shauna, a deaf woman, arrives at their meeting place at the village Spring Festival, she fears a trap and hurries off to meet the couple who plan to adopt her baby. Meanwhile, Dimpna Wilde has her hands full with lambing season and keeping track of her father, so she's grateful for the help of a well-meaning ten-year-old boy, Dylan, at the veterinary clinic. But when the lad goes missing after going into a bog on a dare with two other boys to search for a "monster," she is desperate to help find him. After the adoptive couple are discovered tied up in their home, telling a terrifying story of a deaf pregnant woman being abducted by a man wearing a butterfly mask, Detective Inspector Cormac O'Brien and Detective Sergeant Barbara Neely fear a repeat of a disturbing case from twenty years earlier, when a charismatic leader calling himself the Shepherd, lured poor pregnant girls into his enigmatic cult. Though allegations of baby smuggling were never proven, he'd been put away on other charges. But then they learn that the Shepherd has recently been released from prison. Trapped in a cold, dark room with a frightened boy, Shauna fears for their lives as well as that of her unborn baby. If she has any chance of getting out and away from the Moth Man, as she calls her abductor, she'll have to figure out the truth behind who she really is and how that connects to the ordeal she finds herself in now. But time is running out and her baby will be born soon.