In a Southeast Asian city, an error in the subway’s automated systems causes the last train for the night to veer off-course into a series of old, abandoned tunnels. Among the passengers are a single mother traumatized by the death of her husband in an accident, her young son and the estranged teenaged daughter of the subway’s chief engineer. Discovering that the train’s signal has completely disappeared, the night shift of the train system’s central command mounts a rescue operation as a mysterious creature that made its home within the abandoned tunnels begins attacking the passengers.