三组男女互相产生错综复杂的感情关系构成剧情，首先是本·斯蒂勒饰演的舞台导师Jerry与妻子不和，因而跟有夫之妇Mary发展婚外情。而他的妻子也跟别人交好，可是在她发现Jerry背叛自己时却醋劲大发。另一方面，娜塔莎·金斯基饰演的Cheri也背着男朋友有了新的恋情，三对鸳鸯搞乱一池春水。

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 hun…