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.

Zeynep has been seeing some beings for a while. Upon this situation, Zeynep and her family set out to find out why what happened. Meanwhile, Zeynep's 6-year-old sister, Elif, mysteriously disappears. Although the evidence indicates that Zeynep pushed Elif into the well, no trace of Elif was found in the well for 2 months. When her mother sets out to search for her daughter again, she is forced to face grim realities.