Wealthy children's author Cathryn receives several disturbing calls in her home one night; the female voice on the other end suggests mockingly that her husband Hugh is having an affair. He comforts her, but Cathryn soon finds herself engulfed in apparitions and hallucinations while staying at her remote vacation home in Ireland. Her mental state becomes increasingly unstable, with paranoia, visions of a doppelgänger, and a blurring of reality as she struggles to distinguish between her husband, her dead lover, and a neighbor.