Not an easy review to write because I read the sequel "Wish Me Luck" before I was aware of this novel.
In truth, I suspect that it is better to read the sequel first. The sequel raises the mysteries and provides the answers which works well in "Wish Me Luck". This novel then gives more detail about how the mysteries arose in the first place which is very interesting.
I am not sure, however, how interesting this novel would be if you were not already interested in the characters (from having read the sequel).
My recommendation is, therefore, read the sequel first to put this novel in context.