A young newlywed couple find themselves trapped in a network of underground caves. With her husband injured, the new bride is forced to find her way back to the surface in order to save his life. In the process, they discover a terrifying truth about the "underneath", they are not alone. Something evil is hunting them.。一生沉默如大多数人般的外婆(闫妮饰),突然不告而别、离家消失,游走于城市各地,变得不再沉默,变得特立独行,宛如城市游侠,利刃般刺入无数人的生活,揭开一个个难定黑白善恶的人生,一边改变着自己,一边也改变了许多人——包括外婆的姐姐(闫妮饰)、女儿(张瑶饰)、外孙女(邓恩熙饰)的人生……。