潮湿喧嚣的大都市内，妍舒（郑有美 饰）和未成年的妹妹秀晶（金赛纶 饰）相依为命。秀晶早年因一起事故丧失听力，内疚的妍舒背负着抚养妹妹长大成人的重任，殚精竭虑照顾秀晶的衣食住行。接连一段时间，城市中有女性神秘失踪，而她们全被一个居住在下水道里的男子（郑敬淏 饰）所劫持并杀害。男人曾遭受不幸的童年，黑暗的经历扭曲了他的性格和灵魂。他精心将下水道改造成独立的王国，通过密布在大街小巷的摄像头监视路人的行踪，并锁定狩猎目标。直到某天，秀晶也被这个男子盯上。突然中断的电话让妍舒焦虑不安，为了救出妹妹她不顾危险闯入了危险重重的下水道……©豆瓣

　　A mysterious man, Dean, returns to his hometown of Grimsby after many years abroad in the Army. His arrival is met with animosity, particularly from his father, an avid pigeon racer. Dean is drawn back to confront his demons, and confess a secret to a childhood friend, Jess, only to discover she has been struggling since the untimely death of her husband. Whilst attempting to raise her child and battling a crumbling economy and dearth of opportunities, she is pulled into a harsh underworld. Dean must help her, throw her a lifeline, but the situation only darkens. When their lives are threatened he will do all it takes to make sure she is safe.

一名年轻女子和她的朋友成为了绑架者的目标，他们的豪华轿车被迫驶离道路并坠入运河，他们必须尽一切努力求生。