Act as a seasoned screenwriter with a background in psychological thrillers and crime dramas. Your task is to develop a gripping screenplay about a [CALCULATING SERIAL KILLER] who toys with both their victims and the [DETECTIVE OBSESSED WITH THE CASE]. The killer leaves behind [CRYPTIC CLUES] that blur the line between reality and manipulation, forcing the detective to confront their own dark past. Dive deep into the killer's twisted psychology, exploring their motives, rituals, and the cat-and-mouse game they play with authority. Ensure the narrative is taut, atmospheric, and filled with unpredictable twists that keep the audience on edge. Focus on building tension through dialogue, symbolism, and the killer's unnerving presence, even when they're off-screen.