I received this book as a Christmas present and started reading it without really knowing what it was about, apart from a vague idea that it might have something to do with vampires. I was hoping for an epic adventure, and I definitely got it! Without revealing too much of the plot, it is sort of about vampires, but mainly about how humans deal with an apocalyptic event and what happens afterwards.The book is split into two parts - before and after the life-changing events and the first part was amazing. I just loved all the stuff about humans trying to contain a crisis, FBI involvement, child smuggling, medical research gone wrong and crazy nuns. The pace was brisk, the plot was interesting and it was easy to engage with and relate to all of the characters.But unfortunately, the part about after everything had gone wrong was just OK. And this was about two thirds of the book. There was a really abrupt shift between before and after, which was a bit disorienting, and I found the newer characters harder to relate to and identify with. The writing seemed to suddenly get a lot more waffly too, and the book began to remind me of a Stephen King novel. A character couldn't be introduced or reintroduced without Cronin telling us everything about them, including their early history, likes and dislikes and probably even what they had for breakfast this morning. This slowed the book down considerably and there were parts where I was thinking "just get on with the story already!".That's not to say I didn't enjoy reading the second section - I did - I just think it could have done with a good edit. The story ideas were still good (although I think Cronin copped out by giving someone superpowers to keep everyone else safe) and the plot still interesting, I just wanted things to move faster and the tension to remain high.When I read this, I wasn't aware that it's apparently the first book in a series or trilogy and consequently was a bit disappointed with how unresolved the ending was. Now I know it's a series it does make more sense to leave some loose ends but I can't help but think that Cronin should have been able to tell the whole story in a book of this size. Maybe it's because series are popular with publishers?After all of the above moans, I should say that I did enjoy reading this book. It's hefty, for sure, but it's an easy read and some parts are truly unputdownable. I'm unsure as to whether I'll read the next one when it comes out.