Sorority Row (2009)

"The sisters of Theta Pi are dying to keep a secret."

Plot Summary

When five sorority girls inadvertently cause the murder of one of their sisters in a prank gone wrong, they agree to keep the matter to themselves and never speak of it again, so they can get on with their lives. This proves easier said than done, when after graduation a mysterious killer goes after the five of them and anyone who knows their secret.