On their last weekend together, Megan and Abby Graves are lost in a remote part of the Arizona desert where they are lured to Skull City Mine, an abandoned mine town. But they soon learn Skull City is anything but abandoned — and there’s no way out. The sisters are now prey, forced to unleash their most primitive instincts in a desperate, all-out battle for survival against unspeakable horrors — both human and supernatural. Can they unlock the terrifying secrets of Skull City in time to save themselves or will they become the latest in a long line of victims?