The overall narrative is pretty good in providing a nice flow of storyline and adequate structure for its backstory, though the visual impact on its horror elements might be a little lackluster and falls short in terms of attention to details. Despite that the logical reasoning at the end is relevant enough to justify the grudge held in the train station, and it even comes with a spy-like mission ending for the final resolution, which is a pleasant surprise and a fresh take for Korean horror films.