Carla has a happy life, she is a well respected journalist, has a loving, supportive boyfriend and a great relationship with her younger sister Rachel. But after her sister tragically dies when she falls through a loose safety railing on a cliff edge, life will never be the same again. Struggling to come to terms with her heartbreaking loss she is cruelly tormented by haunting visions of her sister. Becoming terrified of heights and developing an extreme fear of falling has left her unable to work, and driven by the fear of losing her mind, Carla joins a group of Acrophobics who are taking part in an experimental treatment led by Dr. Sadowski. In a desperate attempt to try and move on with her life Carla makes friends with the group members only to become more terrified as one by one they die in mysterious circumstances. Is this all in her mind or is something or someone more sinister at work?