Lately, DCI Nelson has been receiving threatening letters. They are anonymous, yet reminiscent of ones he has received in the past, from the person who drew him into a case that's haunted him for years. At the same time, forensic archaeologist Ruth Galloway receives a letter purporting to be from that very same person—her former mentor, and the reason she first started working with Nelson. But in this 11th book in the series (after The Dark Angel), the author of those letters is dead. Or is he? The past is reaching out for Ruth and Nelson, and its grip is deadly.