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.
平凡的一天，名叫扎克利和伊森的小男孩在某公园内发生争执，前者用棍子将后者的嘴打破。这起不大不小的儿童纠纷，将两对本没有任何交集的夫妇拉到了一起。经营小百货商店的麦克·朗斯特里特（约翰·C·赖利 John C Reilly 饰）与身为作家的潘妮洛普（朱迪·福斯特 Jodie Foster 饰）是伊森的父母，他们在家中迎来扎克利的父母——律师艾伦·考温（克里斯托弗·沃尔兹 Christoph Waltz 饰）以及投资经纪人南希（凯特·温斯莱特 KateWinslet 饰）——的拜访。他们就孩子的伤害事件协商、
