The Unseen: It Begins; Rest in Peace

Lucy is out walking one night and she becomes convinced that something or someone is following her.Spooked, she ducks into a cemetery to try and lose her stalker and she slips and falls into an open grave only to discover she is not alone.She manages to escape but starts having terrifying visions and dreams and she can't shake that feeling of an unseen presence always watching...and waiting.Who was the girl in the grave and what did it have to do with Lucy?