The story takes place in the future world. A Long (played by Leon Lai) and A Qiang (played by Jacky Cheung) are both special police officers who catch monsters. However, his boss (played by Yuen Woo-ping) values A Long very much, but is wary of A Qiang. A Qiang was so angry that he got drunk in the bar, and was supported and comforted by his girlfriend (played by Carman Lee). However, he was always shrouded in a shadow in his heart-it turned out that A Qiang's mother was also a monster, and later he told this secret to A Long. A Long also confessed his relationship with the monster Huan Ji (played by Michelle Reis)... After that, A Long met Huan Ji, who has now become Yuan's wife, in an operation to capture Yuan Dazong (played by Nakadai Tatsuya), but in a hurry, he had to lead to many misunderstandings. In fact, Yuan Dazong is a monster that wants to cooperate with humans, but there is another liquid monster that is wreaking havoc on the city. In the process of fighting against the liquid monster, the relationship between A Long and Huan Ji experienced the test of life and death, but Yuan Dazong's son Gui Zhongdao (played by Cheung Yaoyang) designed to alienate and destroy mankind. At the same time, A Qiang also discovered a traitor in the special police team...