In the remote depths of Vietnam's Son Doong caverns, a tourist has gone missing. The local police launch a routine investigation, but what they uncover is far from ordinary. As they venture deeper into the world's largest cave system, strange occurrences suggest they are not alone. Ancient creatures, long forgotten and angered by the sudden intrusion, begin to stir. As the stakes rise, the military is called in to face the monsters lurking within the tunnels. But will modern weaponry and strategy be enough to combat terrifying creatures that thrive in darkness?