Pretty Little Liars by Sara Shepard

I haven't gotten a chance to read these yet but I am in love with the TV series on ABC Family. It's a great story!

"After the queen bee of their clique mysteriously disappears during a slumber party on the last day of seventh grade, the remaining four girls drift apart. Now, three years later, the Rosewood, Pa., former pals are practically strangers, but still plagued by the secrets that they shared with Alison and new scandals they are trying to keep under wraps. Then they each start receiving cryptic messages from someone named 'A' who seems to know everything, and makes them wonder, 'Was she back?' The four girls are fairly standard types: there is free-spirited Aria, overachiever Spencer, good-girl Emily, a star swimmer, and glamorous Hanna. Their scandals, too, echo the over-the-top fare typical of guilty pleasure books: Aria is having an affair with her new AP English teacher, for example, while Emily finds that kissing a girl 'felt a zillion times different than kissing' her boyfriend. Readers will certainly find enough drama to keep the pages turning (one girl battles bulimia, another steals her sister's boyfriend and then there's what's buried in Alison's old backyard), and they will no doubt have fun piecing together who and what could be behind those bizarre messages. This is clique lit with a mystery twist: the author has spun a plethora of possibilities sure to make readers reach for the next installment in this planned four-book series and beyond."

Enjoy!