Lin Jingyun, a self-proclaimed killer, entered a mental hospital pretending to be mentally ill in order to avoid being caught by the police. He met Su Shushu, a "witch" who could see elves, Liang Yunqing, who always stared at his "girlfriend on the roof" through the window, Hu Ci, a "cat" who fell in love with a pet rat, Zhao Acheng, an "underground worker" and other mentally ill people.