A serial killer named Caleb Wright kidnaps Officer Lucy Chen as part of a twisted game with the police. He buries Lucy alive in a barrel underground and challenges the team to find her before she runs out of air. While trapped, Lucy struggles to stay conscious and keeps herself awake by singing. Meanwhile, the rest of the officers race against time, following clues Caleb gives them. After an intense search, they finally locate Lucy and dig her out just before it’s too late.