It's been only a few months since archaeologist Ruth Galloway found herself entangled in a missing persons case, barely escaping with her life. But when construction workers demolishing a large old house in Norwich uncover the bones of a child beneath a doorway—minus its skull—Ruth is once again called upon to investigate. Is it a Roman-era ritual sacrifice, or is the killer closer at hand?

Ruth and Detective Harry Nelson would like to find out—and fast. When they realize the house was once a children's home, they track down the Catholic priest who served as its operator. Father Hennessey reports that two children did go missing from the home forty years before—a boy and a girl. They were never found. When carbon dating proves that the child's bones predate the home and relate to a time when the house was privately owned, Ruth is drawn ever more deeply into the case. But as spring turns into summer 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.

The Janus Stone is a riveting follow-up to Griffiths's acclaimed The Crossing Places.