结束了一段破败的婚姻，干练自强的凯瑟琳（伊丽莎白·苏 Elisabeth Shue 饰）带着女儿艾莉莎（詹妮弗·劳伦斯 Jennifer Lawrence 饰）远离芝加哥，搬到了一处位于州际公园丛林深处的房子居住。这里风光秀美，景色宜人，深得母女二人的欢心。美中不足的是，附近一处住宅四年前曾经发生惨绝人寰的杀人案件，失踪的女儿更成为当地人口中盘桓不去的幽怨鬼魂，这一切令人不免心怀惴惴。未过多久，心情烦乱的艾莉莎结识了那户悲剧人家幸存的独子瑞恩（马克斯·希尔莱耶 Max Thieriot 饰）。
短暂的交流让艾莉莎隐隐从瑞恩的身上找到些许认同感，却不知这名看似敏感纤细的男孩，心中隐藏着怎样黑暗的秘密……
五年前，仿佛被魔鬼所控制的凯蒂（Katie Featherston 饰）杀害了自己的男朋友、姐姐、姐夫，并带走他们尚在襁褓中的孩子亨特，不知所终。时间来到2011年，一个平凡幸福的四口之家，美丽女孩爱丽克丝（凯瑟琳·牛顿 Kathryn Newton 饰）过着无忧无虑的生活，她每天和男友本（麦特·西弗里 Matt Shively 饰）通过视频聊天，平日里本也会拿着摄像机随时拍摄。某天，无依无靠的小男孩罗比（Brady Allen 饰）入住爱丽克丝的家，罗比沉默寡言，并声称有一个名叫托比的朋友。爱丽克丝他们起初不以为意，但是渐渐却发现房屋里接二连三有奇怪诡异的事情发生。
在本的建议下，他们在家中各个角落安装摄像头，监控着白天夜晚所发生的一切。屏幕前，令人匪夷所思且毛骨悚然的景象悄悄上演……
A group of tired commuters have caught the last train home, ready to hop into their beds for the night. However, their train soon veers off-course and crashes into an abandoned tunnel. The three surviving commuters; withdrawn mother Yi Ling, her son Lucas, and student Janice, are forced to band together and survive the night, as well as avoid the mysterious monster hunting them. Yi Ling still suffers from flashbacks to the car accident that killed her husband and nearly took Lucas` life too. When Lucas is snatched away by the monster, her maternal instincts are tested, and Janice`s ideas of family are challenged as she remembers her difficult relationship with her estranged father. Back at the subway control headquarters, the engineers do their best to make sense of the situation and rescue the survivors.
