Deputy Sheriff Jess Delgado is tasked with transporting the sole survivor of a mysterious attack along the Texas-Mexico border to CoreCivil, a for-profit immigration detention centre closing down due to wide-spread protests. Housing only a handful remaining detainees and manned by a skeleton crew of disgruntled guards, the detention center becomes a desperate battle ground when something otherworldly emerges from deep below the earth. Something that only fears the light. Deputy Delgado must pull together the guards and detainees - two groups that hate and fear each other - to survive the night. Or fall to the vengeance of the things that live beneath.