Sweet Insanity (2006)

A typical high school senior's friendship with a newly arrived transfer student finds the daydreaming graduate-to-be facing an impossible evil in a sinister tale of teenage terror from director Daniel Hess. Stacy is a hard-partying senior who somehow tolerates her boring classes just long enough to get through the week and cut loose with her best friends when the weekend rolls around. At first striking up a casual friendship with new student Christina, Stacy soon begins to ponder her new pal's mental stability when Christina's behavior begins to border on obsessive. There's something much more malevolent that's coming between the pair than intense emotions though, and when one of the most popular students in the school goes missing and Stacy makes the startling discovery that something evil has followed Christina from her former home, she comes into contact with a formidable force of evil that may be using the troubled transfer student to spread it's influence to a whole new town.