An unidentified figure is captured in a street-view image of Salmokji, a remote reservoir. A reshoot is required to contain the situation—but a sense of dread surrounds the location, and no one is eager to return. Despite the unease, Su-in leads the crew in place of her senior colleague, who previously vanished after visiting the area. The shoot quickly begins to unravel as crew members experience disturbing phenomena that defy explanation. As the deep end of Salmokji reveals traces of something lurking beneath the surface, the team is forced to confront a presence that refuses to remain unseen—and a truth that should have never been surfaced.