This is definitely a book that will keep you wildly turning pages well into the night.  It moves along at breakneck speed right until the end, and just when I thought, "Phew" I made it!", along comes another hit out of left field, and when I actually did shut the book, I had to sit there for a minute take the ending in.  Right up front, I should tell you that this is book 7 in the DI Luc Callanach series, but even though I haven't read the other books in the series, I had no difficulty following along with Callanach and DCI Ava Turner as they are tracking The Edinburgh Bomber in and around the streets of Edinburgh.  The body count keeps piling up, and still they feel no nearer to figuring out the perpetrator.  The secondary story that unfolds within the main story, always marked by "Before" after the Chapter number, made the story come together a bit for me. It also added some context to the plot. I do not want to go into any description of the plot, as this book should be read with no pre-conceived notions, but I will say that the book is a high-octane, twisted, and very intense read.  It will take you for a ride and won't let you off until the very last word.