Julia, a young school teacher with a traumatic childhood, returns home to Savannah, Georgia, after many years of estrangement from her twin sister, Mary. Julia's memories are taunted by their relationship, where Mary was always more aggressive and manipulative. After being released from a mental institution, Mary is still consumed by bitterness and harbors sinister intentions towards her sister. Julia attempts to lead a normal life despite the lingering fear of her sister's jealousy and erratic behavior. As Julia settles back into her old home, the atmosphere grows increasingly tense when she senses someone is watching her and strange occurrences start happening around the house.

Horrified by the realization that Mary's presence is behind these unsettling events, Julia's paranoia intensifies. As her anxiety mounts, the boundaries between reality and delusion blur. Unusual deaths and inexplicable incidents heighten Julia's state of unease as she navigates an agonizing survival battle. The sense of impending doom escalates with each passing day as Julia grapples with the malevolent force seeking to destroy her. Her determination to uncover the truth and protect herself leads her down a disturbing path filled with psychological terror and suspense.