26岁的约翰·琼斯是一名洞穴探险家，他喜欢挑战各种不同大小的洞穴攀爬。2009年，琼斯挑战犹他州坚果石灰洞时，不幸陷入一个宽18英寸，深150英尺的洞中，因为洞穴其中一段的空间实在太过狭小，导致他整个人被卡死。救援人员竭尽全力营救，但是琼斯的身体正在一步步地突破极限……

In an underground facility, five scientists wake from cryosleep with no memory of who they are or how long they've been asleep. They soon make a shocking realization: a killer is hunting them down there, and may even be hiding among them.