该片改编自朝鲜书籍《朝鲜王朝实录》中仅有1页的怪兽故事历史记载。故事围绕着怪兽“物怪”的出现，展开了各方势力为夺取王位而展开的斗争。在朝鲜中宗22年间，一个巨大的怪兽“物怪”出现，开始攻击百姓。遇到物怪的人们，总是被它当场残忍杀害，即使幸存下来，之后也会因沉浸于可怕的痛苦而死去。这让汉阳瞬间陷入了恐惧之中。凶恶的物怪扰乱了国家的安宁，也威胁到了中宗的安危。于是中宗召唤原内禁卫长尹谦（金明民饰）进宫，想除掉物怪。尹谦与多年的好友武官成韩（金仁权饰）、尹谦的独生女儿明（李惠利饰）以及中宗委派的许宣传官（崔宇植饰）一起，组成了物怪搜寻小队，联手对物怪展开了抓捕。在抓捕物怪的过程中，尹谦和他的小队发现了令人难以置信的巨大秘密。

The film is adapted from the historical record of monster stories in the Korean book "Monster". The story revolves around the appearance of the monster "Monster", and the struggle of various forces to seize the throne has been launched. In the 22nd year of King Jongjong of Joseon, a huge monster "Mongolia" appeared and began to attack the people. People who encounter monsters are always brutally killed by it on the spot, and even if they survive, they will die in terrible pain later. This made Hanyang fall into fear instantly. The vicious monsters disturbed the peace of the country and threatened Zhongzong's safety. So Zhongzong summoned Yinqian (played by Jin Mingmin), the former head of the inner guard, into the palace, trying to get rid of the monster. Together with his long-time friend military officer Sung Han (played by Kim In-kwon), Yin Qian's only daughter Ming (played by Li Hyeri), and Xu Xuanguan (played by Cui Yuzhi) appointed by Zhongzong, he formed a monster search team to jointly investigate the monsters. arrested. In the process of catching monsters, Yin Qian and his team discovered an unbelievably huge secret