Ten years after a tragic incident that left their parents dead and their family shattered, siblings Kaylie and Tim are reunited. Kaylie is convinced that their parents' deaths were caused by a malevolent supernatural force residing within an antique mirror in their childhood home. Determined to prove her theory and clear their family's name, Kaylie tracks down the mirror, now in an auction house, and plans to document its destruction to validate her claims. She recruits Tim, who has just been released from a psychiatric hospital where he was treated for his insistence on the supernatural nature of their parents' demise, despite later accepting a more rational explanation for the events of their childhood.

The plot oscillates between two timelines: the present, where Kaylie and Tim prepare to confront the haunted mirror, and the past, unraveling the events leading up to their family's tragedy. In the past, the mirror exerts its malevolent influence on the family, gradually degenerating their parents' mental health and sewing discord. In the present, as Kaylie sets up cameras and monitors to document the mirror's supernatural powers, they begin to experience unsettling phenomena, blurring the lines between reality and illusion, and forcing them to face the horrors of their past. As they delve deeper, the siblings start to question their perceptions and wonder if they can trust their own memories or each other.