Nothing lasts forever. The book that Die Hard is based off of. I have never read a book where I have verbally shouted WTF while reading it before. I did it about a dozen times reading this. The main character is a psychopath. He spends the whole book thinking of the flight attendant he met for all of a few hours. All he thinks about is wanting to bone her. Like every time he murders people it cuts to him thinking about wanting to bone her. When he has other thoughts it's about how all the women he guns down look like his daughter. Then spoiler alert. At the end his daughter dies and he just immediately goes back to thinking about the flight attendant.
He has no remorse for killing any of the people. In fact he's a counterterrorism expert who knows all about the bad guys and so it comes off like he's going through the building killing them in cold blood. Plus they're all very young and like he keeps commenting on that fact. But not in a way that sounds like empathy and more like they deserve to be murdered for being so naive.
Like I can't stress how much of a psychopath the main character comes off as. The whole book is just one abuse of power after another.
This was my answer as well. I've never read a book where I verbally shouted WTF from reading it until I read this. The main character is a total psychopath. Movie is 100 times better.