Demon 3: Desolate Scream tells the story of a young woman who encounters terrible situations while trying to find out what the beings she sees are. Zeynep, who has been suffering from a neurological disorder for a while, begins to experience forgetfulness. Zeynep, who sees some beings at the same time, cannot understand whether they are related to her illness or not. Suspecting that the beings she sees may be from the Realm of the Phantoms, Zeynep sets out to find out. Meanwhile, Zeynep's 6-year-old sister, Elif, mysteriously disappears. The family is devastated by Elif's disappearance. But something more terrifying awaits them.