This was both riveting and disappointing.
By page 80, I was becoming frustrated, as murders were occurring at a rate that would put Cabot Cove, Maine, to shame, and there were numerous apparently unconnected threads, with no hint of connection.
Not long after, the story started to become interesting as it became clear how the various events were interconnected, but it really took too long to get there - most people will give up on a book before I do.
There are two things that I can't stand in mysteries and thrillers: outrageous coincidence - where events don't seem to have cause and effect, they're just placed together for the sake of the story; and the way heroes in these stories feel they have to risk life and limb doing things that would be far more easily and effectively handled by the police. It came as a very pleasant surprise that our hero, Glen Garber, isn't a gung-ho vigilante. When it becomes clear to him (in part because of good counsel from his lawyer) that his wife's death may not have been an accident, he talks to - and convinces - the police. His actions are not unreasonable and he doesn't act as if he assumes that trained professionals can't be as effective as a motivated amateur!
However, in the end the whole story is bogged down by an incredible overcomplexity - relying on that personal bugbear - the coincidence. There is not one killer, but three!: one's a professional killer, who is leaving so many bodies it has to draw attention to a business that wants to remain unexamined; one is a victim of blackmail who's prepared to kill again in a manner that will expose the very thing the first murder was supposed to hide; and the third, an obvious sociopath in hindsight, kills anyone getting in the murderer's way, via extremely convoluted and contrived methods - yet the killer is supposed to be extremely well organized and can't even get rid of the most obvious evidence.
Give me a break...