When a child's remains are found at a demolition site--a former children's home in Norwich--forensic archaeologist Ruth Galloway is called in to examine the bones. She quickly notes that the skull is missing. Is this a Roman-era ritual sacrifice, or is the killer closer at hand?

Ruth and DCI Nelson seek out the priest who served as the home's operator. Father Hennessey reports that two children had gone missing there, about forty years earlier. They were never found. Is this one of them, finally unearthed? Or another child altogether? Ruth is drawn into the case, but soon it becomes clear that someone is trying very hard to put her off the trail by frightening her, and her unborn child, half to death.