While the plot itself is solid and does work, there are quite a few flaws that I found difficult to get past with this one. The writing isn't brilliant, and a reliance on "our lives changed forever" as a chapter ending was a little annoying. There was also a strange pacing of chapters, in a way that made it feel like it was serialised unnecessarily. 
It was entertaining in the sense that you wanted answers, but thanks to easy-to-hate characters and plot points that were clumsily revealed I doubt I'll be reading much more by Walter.