After fleeing the treacherous exomoon Acheron in Aliens (1986), Ellen Ripley crash-lands on Fiorina 161, a penal labour colony for hardened male criminals. But little do the inmates know that a terrifying Xenomorph lurks in the facility's labyrinthine ventilation duct system. With the silent space invader spilling their blood, sheer panic spreads like wildfire, forcing a handful of prisoners to use primitive weapons to stand a slim chance of surviving the nightmare. However, the law has condemned them to rot in a maximum-security prison planet. And now, pure intergalactic terror has a face. As they all hope for a quick death, can the veteran alien killer from the stars eradicate the evil within?