It's a great book and well worth the read; however, if you aren't even vaguely familiar with Brit ( and there is one American one that I know of, plus there used to be some German ones as well ) Cathedral Choir Boy private school for the upper middle to very wealthy, you will have a bit of trouble really understand a bit of the book. It won't totally spoil it it for you, but I felt that you needed the warning.
OTOH..."HEATHERS" is a very "dark" movie made primarily for a teenage girl crowd. You very well may enjoy it, though.