Five years ago Ed Fagan, the serial killer known as the Night Hunter, disappeared. Since then nothing has been heard from him. But now a Dublin newspaper has received a letter claiming to be from Fagan with a chilling message: he's going to kill again. The Dublin Metropolitan Police are inclined to dismiss the letter as a hoax, but when the body of prostitute Mary Lynch is found, they believe the murderer may well be Fagan. Saxon, a former FBI agent who was writing a book about Fagan when he disappeared, is certain that the killer is someone else. So while DCS Grace Fitzgerald and her team sniff at a cold trail, Saxon must somehow convince them to look beyond the obvious. But in a city of shadows and secrets, that's never going to be easy - especially when the truth is so unexpected that even the most astute detective could be shocked into carelessness in the moment of discovery. And carelessness, in the presence of a killer, can be costly...