Lek老師（Arun Phawilai飾）是一名泰拳敎練，一直敎導着一班小孩子泰拳以自我防衛，他們是Wuth（Nuttawuth Boonrapsap飾）、Catt（Sanisa Chindamanee飾）及Pong（Paethaiy Wongkumlao飾）。他們3個人必須照顧擁有心疾的Wun（Darun Tantivichitvej飾），Wuth的弟弟。　　因為Wun突然心臟病發而必須進行緊急的心臟轉移手術，所以他們來到了一個被國際恐怖組織首領Peda（Johnny Ngian）所控制的醫院。　　無可避免地，他們必須捲入這場醫院的嚴峻考驗，英勇小孩及殘忍恐懼份子之間的激烈打鬥就在這里發生……

Agroupoftiredcommutershavecaughtthelasttrainhome,readytohopintotheirbedsforthenight.However,theirtrainsoonveersoff-courseandcrashesintoanabandonedtunnel.Thethreesurvivingcommuters;withdrawnmotherYiLing,hersonLucas,andstudentJanice,areforcedtobandtogetherandsurvivethenight,aswellasavoidthemysteriousmonsterhuntingthem.YiLingstillsuffersfromflashbackstothecaraccidentthatkilledherhusbandandnearlytookLucas`lifetoo.WhenLucasissnatchedawaybythemonster,hermaternalinstinctsaretested,andJanice`sideasoffamilyarechallengedassheremembersherdifficultrelationshipwithherestrangedfather.Backatthesubwaycontrolheadquarters,theengineersdotheirbesttomakesenseofthesituationandrescuethesurvivors.