One of the more disturbing books in the Dalziel and Pascoe series, in part because of the theme of serial child killing, but also because it shows that there are no easy answers. It's a complex and thought-provoking story, and one that easily supports re-reading. There is the mystery, yes, but there is also the psychological study of a village traumatised both by a series of unsolved child murders and by its forced relocation after its valley was drowned by a new water reservoir. It's also beautifully written by a master of prose. Hill brings his characters to full and vivid life, and they will linger with you for days.
Ideally the series should be read in order, and I think regular readers already familiar with the characters will get more out of this book, but it can be read as a standalone. For those familiar with the series, Hill continues to develop the story of his ongoing characters, deftly weaving it into the main plot of the book. Note that there are references to events in the previous book (The Wood Beyond) which are slight spoilers for that book.