The Shadow Society is an amazing book! Not only is it a great story, but there are also multiple positive messages. You should know that there is romance in the book, and the two characters who are in love kiss and for a very short scene are in bed together, but they do not have any sexual interaction whatsoever. What I love about the romance of this novel though is the fact that I felt while reading it, that Darcy and Con have more of a healthy emotional and personal relationship rather than a physical one that goes past what two teenagers should be doing, which is what you see too much currently. You just can't find many books that display such positive relationships like the one in this book.
There is also violence in this book, but even the most intense scene didn't seem that bad.
Overall, I think you should be at least 11 or 12 years old to read this book just because of what you have learned and experienced at that age. It really is a great and well written story!
God bless! :) :*