Fly On The Wall by E. Lockhart

This book is a good book of how people relate to each other when no one is looking.  Oh but to be a fly on the wall, and then Gretchen becomes a literally becomes a fly on the wall.  It's a great book.  I would say for mature audiences just because of some of the content.  There's some sexual discussions.  I liked the book, I would say read it before you add to your library.