The Nun (movie, 2005)

A group of catholic school girls are victimized by a sadistic and jealous nun, "Sister Ursula". The girls drown the nun in a pool of "holy" water. Eighteen years later circumstances arise in which the nuns spirit is released to take her revenge. She possesses the body of Eva, the daughter of one of her killers. In order for the Sister Ursula to be properly laid to rest Eva herself must be killed.