This is the fifth installment in the Jack Caffrey crime series and the focus is directed away from that of the previous three novels. This, unlike the others, feels like more of a standalone story and is only briefly linked to its predecessors. It is extremely plot-driven and feels more like a straight-up crime story rather than focusing on Caffrey's past and personal life as much as is experienced before. I feel this story called for a divorce from his personal life as the focus of the crimes being on children led to this being one of the most heart-wrenching story lines. Police diver Flea Marley, who also appeared in the previous books, is assigned a large portion of the story and I enjoyed seeing both her and Caffrey struggling to solve the crime in their own distinct ways. 
 This novel has only lost a star as I stumbled upon whodunnit early on in the novel. For a portion of time Hayder put me off the scent but it turns out my theories were correct and so I smugly finished this novel knowing I had been right all along. This (while inflating my ego) led to the shocking big reveal not actually being that shocking at all. That isn't to say that this story wasn't shocking, because it most certainly was - child abductions, chilling messages, underground travels and an abundance of false clues and dead ends abound! 
 There may be a lot of triggers in this story for those of a sensitive nature but if dark, shocking and thrilling fiction is your thing, then I can think of no finer example!