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 hunting them.。电影讲述了在未来,温室效应加剧,环境恶化,人们被迫建造、迁居地下城。科学家们苦心研制气温平衡剂,建造地底列车,希望能带领大家返回地表重建家园。然而在排放计划当天,变异巨蜥空降肆虐,毒气蔓延,灾难降临。
幸存者们在列车工程师王戈的带领下,踏上绝境逃生之旅。。