Someone is killing the nuns of 6th-century Ireland; the grisly discovery of an elderly sister of Saint Brigid's monastery—strangled, bled dry, and thrown into a bog—is the first, then a beautiful young nun is found decapitated and hung from a barren tree. The members of the struggling monastic community of Kildare realize that their sisters are being hunted, and slain in the manner of ancient druid sacrifices. In a tumultuous era when tribal kings and rival religions vie for control, the task of finding the killer falls to Sister Deirdre—raised by a druid grandmother and educated by a wise priest—in this second book in the series, following Saint Brigid's Bones.