The Watch (movie, 2008)

Cassie, a psych student, was kidnapped and traumatized as a child by a disturbed person. To exorcise her demons and to finish her thesis, she decides on an experiment in isolation, working at a secluded watch tower as a fire lookout. But once she's alone, strange things start happening. Or is she just paranoid? Cassie is terrified that her past may be coming back to haunt her.