I don't know how this book has received as many 4 and 5 star reviews as it had - does the author have a marketing trick? It has no redeeming features. It is badly written: bad/clunky dialog (countless examples but to give just one, how many FBI Special Agents in Charge would refer to themselves as Special Agent in Charge when talking to another FBI agent, rather than just SAC? None), bad characterisation, implausible characters (of course I'm prepared to overlook a high degree of implausibility, that goes with the territory of thriller writing, but the villain in this one had just such implausible skills given his upbringing that it didn't work for me) and bad/unbelievable plot. Time and time again it was just too implausible. One key section relies on the bad guy staying on a cruise ship for a week and then hacking in to the cruise ship's database and deleting his record. There is then no record to be found. Given the investigation is taking place at the end of that week, don't you think there'd be at least 20 hard copy printouts of passenger manifests on the ship, to say nothing of in the port records etc? I could go on and on pointing out the errors in this but that would get repetitive, rather like the constant and gratuitous descriptions of violence throughout the book.
In short, it reads like a very extended, rather disturbed essay written by a not very talented teenager
I love thrillers - from Lee Child, Harlan Coben, Jeffrey Deaver to name just a few - and I read a lot of them (probably 50 a year - I travel a lot and read on planes to distract myself) so I have to look outside the big names. I won't be reading any more of this guy. I only finished the book because I hate to leave a book unfinished and I was on a 13 hour flight with nothing else left to read. It still wasn't worth it.