Cathryn, a successful children's author, descends into a psychological crisis marked by visual and auditory hallucinations. She begins to see and hear things that only exist in her mind. Struggling with the line between reality and illusion, she isolates herself in a remote countryside home in an attempt to regain her sanity. The isolation exacerbates her condition as she starts experiencing disturbing visions of her husband Hugh, long-deceased lover Rene, and a mysterious man named Marcel, all of whom seem to intertwine reality with fabrication. Despite Hugh's efforts to comfort her, Cathryn's grip on reality continues to falter, as the surroundings and people she encounters seem to transform into something sinister.

To cope with the escalating terror within her, Cathryn immerses herself in writing but finds no solace. Her hallucinations manifest more vividly and grow violent, leading her to question the true nature of her experiences and the people around her. Each encounter becomes a terrifying puzzle as she tries to discern who is real and who is a figment of her imagination. The overlap between her internal turmoil and external events spirals out of control, thrusting Cathryn into a labyrinthine struggle for sanity that grows increasingly desperate.