故事讲述了以刀哥（陈小春 饰）和高飞（彭敬慈 饰）为首的一群普通人，在一场离奇的地铁事故中，遭遇到变异嗜血的生化蜈蚣，众人从一开始的猜忌自保，到…

故事讲述了以刀哥（陈小春 饰）和高飞（彭敬慈 饰）为首的一群普通人，在一场离奇的地铁事故中，遭遇到变异嗜血的生化蜈蚣，众人从一开始的猜忌自保，到最后齐心协力共同对战地底巨兽的故事。影片中凶残无比的怪异巨型蜈蚣、诡谲莫测的地下洞窟、坠落深渊的环线地铁，所有的一切都让逃生之路变的危机重重。

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 The three surviving commuters; withdrawn mother Yi Ling, her son Lucas, and student Janice, are forced to band together and survive the night, as well as avoid the mysterious monster hunting them.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.