康斗(宋康昊饰)是一个平凡又有些糊涂的中年男人,他带着女儿玄舒(高雅成饰)与家人一起生活,在汉江边经营小店,过着安静祥和的生活。康斗父亲熙峰(边熙峰饰)是一个和蔼老人,弟弟南日(朴海日饰)是家里唯一的大学生,却失业没有工作。他时常牢骚并酗酒,对现实不满。妹妹南珠(裴斗娜饰)是个射箭运动员,却常在关键时刻掉链子。 一天,人们聚集在汉江边上,惊奇地发现攀在大桥的桥墩上,一只从未见过的不明怪物。突然怪物窜到了岸边,冲进围观的人群中。康斗想马上带着女儿逃离,但玄舒却被怪物抓走了,这个普通家庭遭受了空前的打击,整个城市也如临大敌,他们该如何面对怪物?The film revolves around Park Hee-bong, a man in his late 60s. He runs a small snack bar on the banks of the Han River and lives with his two sons, one daughter, and one granddaughter. The Parks seem to lead a quite ordinary and peaceful life, but maybe they are a bit poorer than the average Seoulite. Hee-bong's elder son Gang-du is an immature and incompetent man in his 40s, whose wife left home long ago. Nam-il is the youngest son, an unemployed grumbler, and daughter Nam-joo is an archery medalist and member of the national team. One day, an unidentified monster suddenly appears from the depths of the Han River and spreads panic and death, and Gang-du's daughter Hyun-seo is carried off by the monster and disappears. All of the family members are in a great agony because they lost someone very dear to them. But when they find out she is still alive, they resolve to save her.