After a disgraced geophysicist is stripped of her funding, she makes one last-ditch effort to salvage her career by venturing to a remote, abandoned mine. There, she discovers a perfectly smooth, obsidian-like monolith that emits a strange, high-frequency hum. Her scientific partner, a retired archaeologist, believes it's a spiritual artifact, but she insists on a data-driven approach. As they spend more time near the monolith, their perceptions of reality begin to warp, causing them to see disturbing echoes of past accidents and ghostly figures. They must now race against time to uncover the truth behind the monolith before it drives them to madness.
