Aliens in human disguise commandeer a rural airport during a snowstorm. To survive, the people trapped inside must determine which of their own is not of this Earth.

四名电工——帝恩、雷、二世和谢利在检查一栋废弃的办公大楼时，发现了一处时空旅行的入口。狄恩和二世两个人因此来到位于平行异次元的芝加哥，雷和谢利为了救他们也随后赶到，他们发现这这次异元已经被蜘蛛怪物给毁了，只剩下一小群大难不死的幸存者。于是他们想尽办法要回到自己原来的时空……