Troubled by bouts of sleepwalking and disturbing nightmares, graduate student Sarah Foster goes to her university sleep research center for help. But when she wakes up after her first night of being monitored, the world she lives in seems to have changed in subtle, Twilight-Zone-esque ways.

一架飞越喜马拉雅山脉的客机失事迫降在杳无人迹的皑皑雪山之上，好在大部分乘客得以幸存。 但是，大难不死，未必有后福。 幸存者们很快发现了比严寒和饥饿更为危险的敌人——喜马拉雅雪人！